01 Acura CL idle surge
 

Have an Acura CL type s that nobody seems to be able to diagnose.. its gone off to Acura once, fixed the issue for a week (replaced throttle body gasket.. but that was already done by our shop) and it reappeared.

issue is vehicle surges at idle. revs up from idle to about 1500rpm and bounce back. Sometimes it will do it consistently and other times it will only do it if you blip the throttle. no CEL of any sorts. Throttle body assembly has been replaced, idle air control valve replaced, intake plenum was filled with carbon and oil so that was cleaned out too along with new gaskets, checked all lines/intake for vaccum leaks and was not able to detect any (anyone with experience know of suspectible areas on these cars?), cleaned the egr out, and bled the coolant system.

Open to any ideas, cars not in a huge rush to get fixed but its got me stumped :concentrate:

Try o2 sensor
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Before throwing anymore money at it, try resetting the ECU.

I had this problem on my car (1990 civic) and I went through the motions.
(Cleaned IACV, replaced IACV, sprayed carb cleaner everywhere looking for vacuum leaks)

Tried "pulling the hazard fuze" method (which apparently controls the ECU on my gen. civic) but my idle was still the same.

Then I said, f*** it; disconnnected the battery and held the brakes to drain any residual voltage in the system. I waited about 10 minutes and reconnected.

This lead to the "idle re-learn" process where you let things sit (don't touch the gas) with no electrical load until the radiator fan kicks in. Then shut-off the car all the way off (basically to the point of pulling out your key) and start up the car again.

This is all with my car in mind, it might be a bit different for your car.

Good luck.

EDIT:
If you want to try burping your cooling system, send a PM my way. Not sure if your car has a typical radiator cap setup though.