I have a 95 2wd v6. It was idling really low and would die after stopping and trying take off agian and was kicking in and out of overdrive. I had it in the shop and the only thing they found wrong with it was the thermostat. They replaced it and it ran great for about a week. Once the temps went down outside it started acting up again. I then replaced the coolant temp sensor. Now the idle surges from 400 rpm to 1600rpm and will bog down and sometimes die when I put it in gear. It improves once it warms up. It stays in overdrive most of the time now but every once in a while it will kick out. Also it will sometimes die when I let off the throttle and come to a stop. Changing the CTS seemed to change what was going on but not fix it. I am now thinking it may be the IAC valve. Any thoughts? I would really hate to change the IAC and that not be the problem.

 

It could well be the iac, but new ones are known to be finiky as well. Try taking it out and cleaning it before replacing it.

 

The IAC is a very common problem on these engines. There's a good chance that is it. But, which ECT sensor did you replace, the 1 prong or 2 prong? You should have replaced the 2 prong, so if you did, you got that right.

Did you reset the computer after changing it? Everytime you make any change regarding the engine, you must reset the computer! I've decided after all the changes I've made to my truck, that once the computer gets a certain setup in its memory, it won't change it on its own without being reset.

 

I actually changed both of them. The one with the single wire was broke, which was causing my gauge not to work. I am not sure how to reset the computer. If its just disconnecting the battery I had it disconnected while I changed the sensors.

 

OK I replaced the iac, but I am not sure if that fixed it or not. After replacing it I drove it down the road a couple miles and when I got back to the house it was still idling really high. I put it in nuetral and the idle came down slowly to around 700rmp and stayed. I then took it down the highway for about a 3 mile drive and when I got back the idle was surging again from 600 rpm to 1800 rpm. I turned the truck off and started it again and the idle stayed right at 700 rpm. Is this normal after replacing the iac? Will it come out of it? I had the battery disconnected while changing the iac. This is frustrating.

 

If you really want your computer to forget everything, leave the battery unplugged overnight. Also, that is normal for new IAC.

 

The new IAC didn't fix it, so I gave up and took it to the shop. They put a new TPS on and now it is running great again. I hope this fixes it this time. It kills me to pay someone to do such a simple job, but I guess it is better then me waisting money and time just guessing at it.

 

if it starts to act up again you might want to check this. i don't know if the multi-port injected has an egr valve but my 89 throttle body injected does and it went bad. your symptoms sound a lot like what mine did when the valve went south. might be worth doing a vacuum test on it to see if the diaphram is leaking and pulling it off to see if it's clogged with carbon, this will cause the rod in it to stick and it will work right at times and then start acting up again. should only take a few minutes.

 

I have an 87 Dakota 4x4 3.9 2bbl carb ..... I have some of these same issues but am only finding that the MAP...TPS... etc are for fuel injected. Is that true? I look it up at the part store they say I have em but the parts they show me aren't on my truck. I'm having some surging and rough idling... it doesn't know when to high or low idle. Do I have an IAC on this truck that's prob what my problem is.....