Engine rpm going up and down-1000-3000
 

Engine rpm going up and down form 1000 to 3000. No codes or check engine light, in gear or out. Any ideas where to start. I Have looked and cant find anything. Thanks

I've heard of the newer Volvos, 2004.5+ doing this when the ETC gets very dirty. Which year and motor do you have?

Sorry, I should have put that in the post it is a 2001. Wife had it out of town and when she started it to come home the problem started. She drove it about 150 miles home. This morning I started it and it idled at 1000 for a minute or two then started racing up and down again. Very rhythmic, like it is trying to find where it should be. Can feel it going up and down while driving. Still no codes

I'd buy some MAF cleaner and throttle body cleaner and give everything a good washing. If it continues then I'd remove the IAC and clean it too (you need a new gasket to replace). While doing any of this I'd be looking for any broken vacuum lines. And check the condition of the air filter while you are in there.

Thanks, I will clean the IAC and check the throttle although I did clean them not long ago.
Will report back the results

Just wanted to say thanks for the help. Cleaned the IAC and that was it

My pleasure. Thanks for letting us know it worked. Good feedback is gold.