I was having issues with my 2001 4.8 idling when cold, so I replaced the IAC, which fixed the low idle issue. But now I have a high idle problem, and it feels like my throttle body wants to get stuck when I downshift. It doesn’t want to idle down and keeps pushing me through corners. I’ve relearned the throttle about three times, fully cleaned the throttle body, replaced the TPS, and checked for vacuum leaks. Still having issues… any ideas?
It sounds like you’ve done a lot to troubleshoot. Have you checked the throttle cable? Sometimes they can get stuck or misadjusted.
Yeah, I had a similar problem with my truck. It turned out to be a bad ground connection somewhere. Might be worth checking.
Shannon said:
Yeah, I had a similar problem with my truck. It turned out to be a bad ground connection somewhere. Might be worth checking.
I’ll look into the ground connections. Thanks for the suggestion!
Could also be an issue with the idle air control system. Have you tried resetting the PCM? That sometimes helps with weird idle issues.
Definitely check for any vacuum leaks again. Even a small one can cause a high idle. Good luck!
If all else fails, maybe consider taking it to a mechanic. They might have the tools to pinpoint the issue more accurately.