Please help! Idle issues now.

[ChrisAU]

Spray around the intake manifold and throttle body with carb cleaner to check for vacuum leaks. My guess would be IAC, or a gasket leak of some kind. On the throttle body, there is a "bleeder hole" right near the IAC, check to make sure that isn't plugged. Crap can get in there, and block it off, and it affects airflow of the IAC.

My truck has done this twice before. First time, the K&N cold air intake gasket was getting sucked into that bleeder hole, and blocking airflow to the IAC. Second time, I had a vacuum leak in the throttle body gasket. Does it shake at all when idling? My whole truck would vibrate quite a bit.

Well it has a brand new throttle body gasket as of today, all vacuum lines are snug. I'll check for that little bleeder hole you mentioned though. It shakes when the idle drops due to the miss, but in general, no. When warm it idles great except for when it stumbles randomly. Drives perfectly, and the situation is easily remedied by giving it just a little throttle, just to keep it at 750 RPM or higher.

 

[DRAGGIN95]

How does the pintle on your IAC valve look?

 

[ChrisAU]

I'll get a good pic of it tomorrow.

 

[Tempted]

If you have already ruled out all vacuum leaks then you might check MAP and IAC. From there check that the ignition module is working correctly and that all the wires have a good connection and not too much resistance. Seafoam it if you haven't already. Pull the brake booster vacuum line from the intake and cap the port, then run it around the block.

 

[ChrisAU]

I'm going to make sure all the plugs are tight tomorrow too. Can you elaborate on what you mean with brake booster vacuum line?

 

[Tempted]

I'm going to make sure all the plugs are tight tomorrow too. Can you elaborate on what you mean with brake booster vacuum line?

Looking at the front of the reservoir, the booster vacuum line will be top left of the booster. The line goes from there to the throttle body with a one way check valve somewhere in it. Pop the line off at the throttle body and cap it. This will rule out a brake booster vacuum leak. It probably isn't the issue, but if you have tried everything else then you should try this just to check. The booster uses a lot of vacuum. This is why that if you jam the throttle real hard, then immediately slam the brake pedal you will get something that feels like an ABS stutter. When you hit the throttle the engine vacuum will decrease to nearly nothing and will not let the brake booster work. If there is a vacuum leak somewhere after the throttle body in the brake system then when you cap it the issue will resolve itself and you know that there is a vacuum issue.

 

[towman]

when you had the dist out did you turn it by hand? any rough spots in it, the dist in the throttle body trucks is a weak spot for them

 

[ChrisAU]

Distributor turns like its brand new, nice and smooth. Thats a good idea with the brake booster, I have noticed what I think is it stumbling down to idle when I hit the brakes sometimes...

 

[ChrisAU]

I would like to say that it doesn't have to be driven however; I can start it up cold, let it warm up, and it will start stumbling as it gets warm and eventually stall.

 

[JonZ71]

idk if someoen mentioned this but coil and coil pickup?