I have a 2004 rx8 with 98xxx on the first engine. All is well except for a weird idle surge I keep having at start up. It idles normally high and then when it drops and starts to warm up the idle starts to surge as if im starting it in extreme cold. It will go from 1,500 rpms to 2,000 rpms just reving itself. It only happens when the engine is cold and has not been driven recently. (by cold I mean engine temp. It happens in all outside temperatures) Once it does the idle surge for a good minute the car starts to idle normal and drives fine. I have put in the clutch to see if it is the neutral position sensor but this hasn't done much of anything.

 

Nopes that sounds pretty normal..

If your 8 has been parked for a few days, then it may do that.