So I just had this happen yesterday when I was on the freeway. I let off the gas but the Rpm's didn't dip back below 1000 like normal when idling. But then it went back to normal and idled below 1000. Then again today when just city driving the car would stay at like 1500 rpm's then dipped to about 1200, and would not go to normal. And the car was very slow to decelerate. And at one point it did dip below 1000 then it bounced back up to 1200. When I was heading home it went to normal. Never had this happen before last night. Im guessing its because im at 171,000 miles now and Im sure the tranny is meeting its final miles. I know the montes come with great trannys especially the HD trannys. But I need opinion if this means its going out, and also if I can do it cheaply and repair, instead of having to buy a new one. Worst comes to worst I go to pull-a-part junkyard and yank one off one of the montes there. Any help or advice?

 

I had similar issues with my '07 sitting on the highway. very erratic idle when creeping along. I was fully believing the trans was shot. I did two things.

1) trans flush and filter change. It needed to be done anyway.

what i believed to fix the issue:

2) cleaned the throttle body! mine was really gunked up bad with carbon. cleaned the mass air flow sensor too. I bet you see better performance once you do that. There is a two pack of cleaning fluid you can buy at walmart for each part.

I saw a little improvement after number 1, but super awesome improvment after number 2.

cheers!

 

Now for cleaning the MAF sensor and my throttle body whats the easiest way to going about it? Cause the MAF is very delicate. Or should I just go on to youtube and look?

 

Yeah, I just went to youtube and watched videos.

for the MAF, when I pulled mine off there was a film of lint on the screen. I just cleared that off and sprayed through the protector screen. it isn't hard to remove.

throttle body isn't either. a deep well 10mm socket will help the process.

cheers!

 

Yea it was very easy since I have a CAI and I noticed it improved response time and fixed the idle, thanks for the help