As far as I can see in this forum this is VERY common problem for v6 when you ride at 20-40 km/h and engine dies despite of smooth idle at park. With my car I had the same for a pretty long time. Now the problem is resolved.

Here is the procedure.

Conditions:
1) correct spark advance
2) no ignition problems (good plugs, wires and distributor)
3) no big vacuum leaks
4) good IAC
Now to do:
1) screw out throttle adjustment bolt untill throttle is completely closed
2) turn on ignition and wait 5 sec.
3) disconnect IAC plug
4) run the engine
5) turn throttle adjustment bolt untill engine revvs up suddenly (you need to find this threshold) and add 1/2 turns more
6) shut off engine
7) connect IAC
8) disconnect negative battery cable to reset ECM
9) connect battery
10) run engine

That's all.

p.s. the problem was in incorrect throttle adjustment.

 

Sounds good.. But should one reset the TPS after setting the TB?

 

The 90-92 3.1 motors have non-adjustable TPS unless you remove the idle stop cap and either use a scanner or probe the wires.I do agree with Madathlon that if it was adjustable to do it.I am new to the forum and wanted to add some problems I been experiencing on my car.It was stalling about everytime I came to a light,and start right back up again.I tracked it to a bad brake booster,after that it didnt do it everytime,but still did it.I then found that the divertor valve on my air pump wasnt holding vacuum,which is tied with the fuel pressure regulator.Long story short these engines hate vacuum leaks.Great site I have come back to it on a regular basis..

 

I have a 88 and the TPS is adj, And I been tearing my hair out dealing with a stalling problem.. and Jest a few mins ago I broke the IAC AGGG!!!!! So tomorrow I have to order a new one..

 

no. it is not adjustable.

 

I found new problem with my car.

It is 1992 and many stuff on it is worn. Trottle mountings are worn too. If you try to shake throttle lever where the cable connects to you will see that it moves slightly up and down in left mounting. It is more than enough to stop engine at idle and make idle rough because at closed throttle even small air leak causes unstable idle. This air leak it not "visible" to ECM.
Now start engine and try to shake throttle lever up and down. you will see that it affects idle.

Moreover, it become worse when the engine heats up because all gaps are supposed to increase.

What to do? Thinking....

 

I know for a fact that on a 88 2.8 the TPS is adjustable..

 

on ANY 2.8 it is adjustable. You dont need to adjust it on a 3.1 because the computer takes note of the voltage at startup and uses that as a reference.