So I've been having this problem with my truck now where it won't idle correctly and dies. It started about a week ago when I was driving to work and had a trouble starting it. It would crank and crank and nothing. Got some starting fluid from the gas station and sprayed some in the intake and it would run off of the fluid for however much I had in it. As soon as you cracked the throttle, it would just die. So we thought I wasn't getting any fuel pressure. Took it to a shop nearby (which I normally don't do, but we were expecting a foot of snow so I didn't want to deal with it).

I know the owner of the shop and he said he couldn't get it to start in the parking lot but pulled it into the shop and in the morning it fired right up. He hooked the scanner up to it and did some fancy stuff and eventually replaced the fuel pump. It ran fine for a few two days but now is doing the same thing. I come to a stop light and it wants to idle at 300 rpms then die unless I don't feather the throttle.

Could this be the IAC? I replaced it around a year and a half ago, but could it have gone bad since then? What other things would you guys recommend?

 

If it stays running by feathering the throttle, I would lean IAC or TPS.

 

Is there a way I could check them? Sorry, I haven't had any of these smaller problems in a long time haha. Been dealing with a bad transmission and motor...

 

Well, the IAC you should be able to see moving at key-on.

The TPS, I don't remember the voltage values associated with one that's working.

 

You can test the TPS with an Analog multimeter. Just watch what sensor signal voltage does as you open the throttle. Should be less than 1 volt at closed, and greater than 3.5 at WOT. It should rise smoothly, if it bounces around, or, is out of range at either end, replace it.

Remove the throttle body from the intake, pull the IAC out, and clean the IAC well, and the pintle on the IAC REALLY well. (leave battery disconnected while cleaning.) Put it all back together, and start it up. Might take the PCM a few to re-learn how to idle the engine, but, if it still acts strange after that, and TPS tests ok, replace the IAC.

 

So do I need to have the motor run during this or just have the key on?

 

Key on.

 

Awesome thanks!

 

Engine off.