My 01 Prelude when I put it into park and pump the break the car revs up 500 more than idle and then come back down when I stop, but when it comes down to idle my car shakes a little like its about to stall out. I have an automatic by the way does anyone else have this happen to them? Also it seems like there's a rotten egg smell comming from the bottom of the car does anyone know what the hell that is?

 

rotten egg = bad cat get a new cat or get it removed that might also fix your problem!

 

Sounds possibly like a bad IACV (idle air control valve); it's meant to compensate for changing loads on the engine and maintain a steady idle, but it sounds like it's not doing its job very well...