Trooper refuse to start unless primed by petrol and idles unevenly thereafter

double posted why, ? please add to 1 post,
by edits or comments, please'
there are 3 , v6 engines, you never said which
why ask us, about parts, we dont sell parts
and would have to read the same books on parts as you
why ask use to do that.?
here is the list
USA only, RODEO, prime examples. the GAS v6 engines. 3.1L 3.2L 6vd1 SOHC, one cam per head, then the optional... 6vd1w DOHC, 2 cams in one head, w = DOHC optioned heads, then came... 3.5L (a stroked out, 3.2L.) 6ve1 are all DOHC engines. and have 24 valves. (6x4) with 2 rear cam sensor, used for VVT and spark both,
the engines must match ,to mix parts

here im at isuzu.com parts page
note it changed on August 99, mfg build dates. so.....
tricky
this will not cause low MPG
it will cause idle controls to be dead.
why not post all symptoms, first. and stop guessing?

you need to set the timing to top dead centre and the flywheel has a little knotch in it set that at 6 oclock will start then

dust on your abs sensors needs cleaning

Who performed your last service? If it was fine before, and now it's acting up, then maybe there is a loose electric connector or vacuum line when everything was being buttoned up.
Please let me know if I may further assist you. -TXTEXAN

by the sound of it...the fuel mixture is off...did you get a reasnt tune-up?

check fuel pressure regulator also idle air control solenoid.

check for spark at the coils under load. May have to change some ignition coils.

I had the same issue on my 99 Trooper.

It would usually start when completely cold, but idle around 2k RPM.
It would drive fine. But if I shut it down, ran into a store, and came back out, it would start but immediately idle.
Had to ride the gas a little to get it into gear.
The Check Engine light has been going on and off for 6 months or so.

I took this to my local trusted repair shop (no Isuzu dealers within 200 miles).
The diagnosed the light, and found that the Intake Gaskets were bad or leaking.
The idling problem was related to the car not being able to control the amount of air coming in.

They replaced the Intake gaskets by the next day, and I haven't had a problem since. And no more check engine light, which has been on half a year.

Here's some details from my bill:
(1) Intake Gasket set $107.95
Misc materials $21.00
2.1 hours of Labor

The total cost to me was $345.00, and I definately don't feel gipped.

I had the same trouble with my 93 Trooper.

I went on a sensor-changing spree.

The one sensor that fixed this idle problem was the throttle position sensor.

You can get one here.

Throttle Position Sensor

It's very easy to change, and fixes the problem instantly.

Good luck.

yes they have 2 cataletic convertors, one each bank
there is EGR codes, but only front O2 sensor codes and fuel trim codes no CAT codes
what were the scanner codes or flash codes i can work with both for helpful info
you can read codes by bridging pins 5 & 6 with ignition in on position engine not running