Battery died and replaced but now hard shifting, high idle and will suddenly quit running. Could this be the ECM?

car turns off while driving without warning - 1998-2002 ...

https://www.ifixit.com/.../car+turns+off+while+driving+without+wa...

iFixitwhat would cause my car to turn off while driving & what cause it to start with ... Before you do these, you may consider doing a quick check of your battery terminals. ... So changing out the ignition control module is not a one fix for life job. ... and all thesudden the check engine light would come on and the car would die.

Diagnosing Intermittent Stalling Issues - Underhood Service

www.underhoodservice.com/diagnosing-intermittent-stalling-issues/

Oct 1, 2008 - Replacing a perfectly good ISC motor or solenoid won't fix the ... If the engine stalls while idling or driving, the engine may be running ... The engine may startand idle fine, but run out of power or even stall at highway speeds. ... If the engine is running normally one minute, but suddenly quits, .... Then dies.

Engine Performance Problems Due to Crankshaft Position ...

It sounds like some thing you have done if the fault started after the tune , did you check the gap on the new plugs, check the firing order as it may be messed up . 4 cylinder 1342 6 cylinder 153624 in direction of rotation.

Probably not the ecm.. look for bad plug wires, vacuum leaks, timing settings, Crank Position sensor, Spark plug wires incorrectly installed, Try this.. Open the hood at night and look for the plug wires leaking.. you are looking for sparks.. I would look for disconnected Vac. hoses, broken or cracked vac hoses, ..

bad ecm and or pcm connections,

I would start with the vac leak idea.
And is the check engine light on when it is running ?
If so you should have the computer checked for trouble codes first.
There has to be a source for extra air coming into the intake or throttle body for the engine to run fast at idle, assuming the idle air control valve is working correctly.
That air source has to be found and fixed first.
It could even be the throttle plate not closing completely.

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.

Dissconnect the battery for a while. It will "re-learn."

INSTALLING NEW BATTERY.WHEN DISCONNECTING BATTERY CABLES THE ECM WILL LOSE IDLE CONTROL MEMORY.TAKE TO MAZDA DEALERSHIP LET THEM RESET ECM SO CAR WILL IDLE STOP STALLING AT STOPS.

The high idle cam is on full warm up probably because the choke pull off is not working or the flap is sticking

remove pos cable from bat for 30 secs then re conect to reset computer