negcamber

While the intake manifold was off the car, did you try to clean it? If so, did you leave the IAC in place? If yes to both, then it's likely you have a sticking IAC. All the crud you tried to clean out, ended up in the IAC.

xyzzy

I had a similar situation when I installed my Hondata gasket (yes, a royal PITA). During the install, I also removed the MAP sensor to clean its port but didn't realize the o-ring fell off before reinstalling it. I had large idle fluctuations and a smoke filled garage. I moved the vehicle out of the garage and found the o-ring on the floor. Once the o-ring was back in place, the engine ran perfectly.

Did you remove the MAP sensor during your install?

tekka01

yeah i did, i'll check that too. i was doing a search that low coolant levels could cause the idle to fluctuate? is this true?