Hello, my car is a 1987 325e I have had it for 3 days now and it was working alright until i decided to fix a slightly erratic idle!  

Here is what i did.  

I noticed the idle would go between 750 and 800 randomly.  So i assumed it was a dirty ICV .. i was right.. it was almost completely black inside.. i i cleaned it out with throttle body cleaner..

I then turned my attention the the rest of the intake system.  I checked the box and it really could use a new filter.  But also the intake pipe after the MAS was all greasy and dirty.. so i cleaned that as well... along with the MAS itself which was also in the same condition.  I reassembled everything, let it sit a little while so any remaining throttle body cleaner would evaporate..  started it up and it almost redlined.. I forgot to plug in the ICV.. so i did that.  Turned the car back on .. idled perfectly.  Once i started driving and put the clutch in .. it would rev up to 1200 the drop back down..  and i don't know what is wrong with it? Everything seems to be hooked up correctly?  Here are some things i have tried:

Checked all the connections

While running the car i unpluged the MAS and it would stall out.. i figure this is the problem.

I noticed the MPG guage was just going back and forth as the revs went up and down..  Not exactly sure how this works but i assume it goes by a MAP sensor..

Any help would be great..  

Thanks!

high revs going up and down is mostly caused by the MAS sensor but i think it's better if you check the car for present fault codes


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I know you checked the ICV but i know with mine i have a loose connection hooking into the IVC. Sometimes my idle fluctuates.