Hard starting hot of cold

Idle air solenoid and/or intake vacuum leak.

what engine, 16valves, or 8valves. silver top or black?
MPI or TBI engine. they sold both and are vastly different.
hums dont mean a thing, only that the pump can make noise.
pressure rules (and flow #1)
ive personally fixed every fail possible on these, stalls.
owned many and fixed more. (own 3 and restored them to 100% )
unfortunately this older car is not OBD2 level ECU/PCM.
so no scan tools work.
Ever give it a tune up.? at the 60k mile interval.? repeats?
1: spare parts, both filters. and timing belt?
2: EGR ,main loves to stick open if it does engine will stall.
starts fine , yes
does engine get to 180F coolant temp and hold? if not fix that first.
is engine idle at 800RPM, hot? y/n? if yes, EGR is not stuck open.
if lower, EGR stuck. or other probs.
not knowing which engine makes answers hard, and only generic.
not knowing the transmission option too, makes it hard. 3,4,5speed.?
the 3sp can have vacuum leaks that can be real bad for the 16v engine, see? see how the work together? or not?
3: bad TPS.
stalling happens for 2 reasons (not counting bad engine)
the ECU (engine EFI brain, puter. etc) does all it can to stop stalls
it has 2 slaves to do that. one is ISC other is spark timing.
when stalls happens this is a warning that the ISC is bad,
or is overloaded.
A: MISFIRE. Gross.( 50 reasons, but can be to rich or just needs a tuneup.)
B: bogging . Gross (too lean, or called fuel starvation)
my questions.
does hot idle run at 800 all the time. RPM.
does engine have full power on hills.
does engine stall coming up to traffic stops (EGR malf)
does the lost power. recover, with just holding throttle down? only?
can you tell the difference from bog and misfire.
bog is lack of power, its smooth
misfire is violent, it shacks the motor. does it?
when you pump the throttle, this engages ENRICH mode
in the ECU , and overrides lean,.
my guess, (cant drive it and if could , i can tell whats going on)
but based on your inputs, it say its lean.
if power is low on hills, i then.
grab my fuel pressure gauge. $20
i do this at every fuel filter change, since im THERE already
it has a test port, a 6mm plug.
i take this hose and check for 30psi,
see why guess here.
34 to 36PSI, key on, 3 times, (both engines, not stated, so..)
see the tool here,for next to nothing. costs.
http://www.fixkick.com/INJECTORS/pump.html

the EFI totally can no work at 20 PSI or hums.
it must be at leas 34psi.
below 28 the injectors fail. (read injector spec, and see that)
if the pressure is good there is hope.

post engine type, 4 injectors or 1.
and can go way deeper and more accurate.

bogging is here
http://www.fixkick.com/power-index.html

which engine,? the have up to 3 choices.
rih?
what are the full symptoms,
did you do the full listed 60k mile tune up on car?
sparkplugs,wire, cap rotor/filters? no engine runs right with bad spark
unless it's a diesel.
starts good
runs good or bad hot or cold engine
idle at 800 RPM hot?
stalls> when hot and cold engine
lost of power
bogging
misfire,
learchs>

only stalls , but runs perfect even up hills, at wide open throttle.
fresh gas, or 1 year old?fuel.
can your fast right foot , save the stall, and easily?

ok stalls 101.
1; lost 12vdc to EFI system.
2: lost engine compression.
3: lost spark.
4: lost fueling or floods
there is a simple test for each.
do you want more guesses, or how to do tests.
can do both, but my guessing fails 99 /100 times.

tune it up
do the right foot test. those are always first. on stalls.
always.

check all fuses.
cuts out hot or cold engine.????????
if it wont start and car gets 60k tuneup (?)
then connect scan tool and crank for 5 seconds.
see if you get scan DTC errors , cranking (release key) see em?
stalls are caused by over 50 reasons. guessing is impossible or very expensive.
enter: Diagnosis,
you take measurements, and find the failure path then work that path like bird dog.
2.5L 4cyl engine. I just sold min last week. with 5sp M/T
cuts out, does that mean the engine stalls?
we need to know what it really does.
1: stalls (engine rpm drops to 0 RPM)
2: engine rpm drops to 300rpm and shakes.
3: power loss from engine?
4: only stalls at stop signs...?
5: bogs all them time, same as #3
6: engine misfires (shake)
7: bogs only on throttle TIP-IN then recovers.
8: bogs only on hills.

i wait.
when dead, is spark lost?

I would look at the cold start injector first and work from there.

Its cold start issues:----
Go through the list of help links mentioned below:----

Click the link :----

Cold start problem and vehicle shudder around 2500 to 3500 rpms
http://repairhelpcenter.blogspot.com/2012/10/cold-start-problem-and-vehicle-shudder.html
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Low idle when cold out side?
http://repairhelpcenter.blogspot.com/2011/12/low-idle-when-cold-out-side.html
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Ford explorer 4.0 will not idle when cold?
http://technoanswers.blogspot.in/2012/02/ford-explorer-40-will-not-idle-when.html
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Automatic transmission shift lever hard to move on cold mornings?
http://technoanswers.blogspot.com/2012/01/automatic-transmission-shift-lever-hard.html
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Car won't start when cold?
http://schematicsdiagram.blogspot.com/2011/12/car-wont-start-when-cold.html
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It can be issue with IAC( idle air control valve) causing the problem.

There are many other possibilities causing these idle issues. Engine idles rough.

There are few help links with solutions to troubleshoot such idle issues.

I suggest you refer the link below and follow its troubleshooting details:------

Click the link below:-----

Ford Expedition IAC valve replacing

http://technoanswers.blogspot.com/2012/12/ford-expedition-iac-valve-replacing.html

Bad miss at idle?

http://technoanswers.blogspot.com/2012/01/bad-miss-at-idle.html

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Stumbling and stalling at idle after engine rebuild?

http://schematicsdiagram.blogspot.in/2012/03/stumbling-and-stalling-at-idle-after.html

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1999 Ford F-150 Idles rough and quits when gas pedal is pressed less?

http://technoanswers.blogspot.in/2012/01/1999-ford-f-150-idles-rough-and-quits.html

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Engine stumbles coming off idle when warm?

http://repairhelpcenter.blogspot.com/2012/01/engine-stumbles-coming-off-idle-when.html

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Erratic idle on car?

http://schematicsdiagram.blogspot.com/2011/12/erratic-idle-on-car.html

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Cold start problem and vehicle shudder around 2500 to 3500 rpms

http://repairhelpcenter.blogspot.com/2012/10/cold-start-problem-and-vehicle-shudder.html

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Low idle when cold out side?

http://repairhelpcenter.blogspot.com/2011/12/low-idle-when-cold-out-side.html

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GMC Sonoma Stalls and idles low

http://technoanswers.blogspot.com/2012/10/gmc-sonoma-stalls-and-idles-low.html

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GMC Idle Air Control (IAC) Valve Replacing?

http://schematicsdiagram.blogspot.com/2011/12/gmc-idle-air-control-iac-valve.html

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1996 Camry intermittent engine failure while idle?

http://repairhelpcenter.blogspot.com/2011/10/1996-camry-intermittent-engine-failure.html

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Engine quits at idle?

http://repairhelpcenter.blogspot.com/2011/10/engine-quits-at-idle.html

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Car overheats and Air blows hot at idle?

http://howtobyme.blogspot.com/2011/11/car-overheats-and-air-blows-hot-at-idle.html

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High Idle Problem

http://repairhelpcenter.blogspot.com/2012/10/high-idle-problem.html

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While stop engine idles like cylinder missing?

http://schematicsdiagram.blogspot.com/2012/01/while-stop-engine-idles-like-cylinder.html

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Idle flair is noticed on car? Rough idle? car will not idle? Erratic idle speed?

http://technoanswers.blogspot.in/2012/02/idle-flair-is-noticed-on-car-rough-idle.html

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High rpm in neutral? Inconsistant high RPM in neutral?

http://technoanswers.blogspot.in/2012/02/high-rpm-in-neutral-inconsistant-high.html

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Vehicle stumbling at idle and shows code 54?

http://schematicsdiagram.blogspot.in/2012/03/vehicle-stumbling-at-idle-and-shows.html

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Rough idle, staling and Erratic shifting?

http://technoanswers.blogspot.in/2012/03/rough-idlestaling-and-erratic-shifting.html

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While stop engine idles like cylinder missing?

http://schematicsdiagram.blogspot.com/2012/01/while-stop-engine-idles-like-cylinder.html

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These details will help.

Thanks.

Your only problem friend, is the temperature sending unit/sensor. Upon cold start, this sensor wil tell the computer to go into cold start mode putting a bit more fuel in and raising the idle a bit to keep it running when cold without using the throttle. Replace that sensor and your good to go. Makes sense, right?

IAC valve has gone bad. Its located on the throttle body and is what controlls/keeps the vehicle running at idle.

Did you replace the fuel filter ? There is NO WAY TO CHECK a fuel filter. Because fuel comes out of the feed side of the filter does not mean its not clogged. It could restrict under pressure. I say , start by REPLACING THE FUEL FILTER. There is also a screen in the tank attached to the pick-up. It also gets clogged at times. Hope this helps.