I recently changed my valve gasket covers and I did leave the plenum piece with the throttle body out in the open for a couple of days. I was wondering if this might have to do with the throttle body needing to be cleaned or anything else besides that. The car rattles and shakes when I was inside and from the outside the exhaust idle is more jittery. When I went to drive it around it didn't feel the same. Hopefully you guys can help thank you.

 

Did you unplug the TB? If so you MUST do all the proper relearns for everything to function properly. It's also a common mistake to accidentally pinch the oil fill neck between the two plenum halves when reassembling everything.

Do all these resets in order.

https://nicoclub.com/archives/g35-35...procedure.html