I have a b18a1 that does not idle correctly. The rpms rise and drop from approx 1200 - 2500 rpms at a times.

The engine runs smooth though when in gear.

I'm throwing no codes.

I have taken the valve on the back of the intake manifold ( coolant runs through it) off and let it sit in seafoam for approx 15 minutes. I did not completley take it apart, only the piece that's held onby 3 screws. The other bolt looking thing I don't have the proper wrench for.

Do I need to take that off too? Should I try a different cleaning method?
Should it sit in some cleaning soloution longer then 15 mins?

 

check to so if your low in coolant that will do it and if your good replace iac valve cleaning it dosen't work just replace it.assuming no vaccume leaks are present

 

sounds like a vacuum leak, unplug it and see what the car is idling at.