Hello everyone!

I'm pretty new to the forums and still learning how to navigate, but I need any and all help. I've got a 98' 2WD with the 3.4L and it's idle is 2000 rpm when I first crank it and drops to 1500 after it's warmed up. I've done everything I know to check for high idles: MAS, TPS, spray the bay with carb cleaner for vacuum leaks, etc. I eventually unplugged the IAC and the idle dropped to 1000 rpm, which is definitely better than what it was but still high. Is there anything else that could be causing this high idle? Also, is it bad to drive with the IAC disconnected? I see a lot of others have the same issue but haven't gotten it solved. I desperately need it done cause its eating gas like crazy and gas prices don't help lol.

Thank you in advance for any hints

 

Has this symptom started out of the blue? Or has your idle been high since you owned the truck?


If it’s been high for a long time, or slowly getting worse, I would say you could use a good upper intake and throttle body cleaning. Take the intake snorkel off leading to the throttle body and look at the butterfly of the throttle and see if it’s all black and carbon coated.

The IAC tries to correct running issues on the intake side been adding fresh air and leaning out the fuel mixture. It’s possible that it is gummed up and the little plunger isn’t moving the way it should.