IAC valve. The idle control valve will cause it to jump idle or hold a high idle. Some cars you can take it off, clean out the carbon and you're good to go. if that doesnt fix it replace it. I'm not sure where yours is in an 02 model. the high idle will cause the car to move without touching the gas and hard to stop. You can also check the throttle cable adjustments and take the intake boot off and check the throttle body. If it's too dirty it may cause the throttle plate to jump to compensate just to keep air going to the engine. So check the throttle body, clean it anyway because it'll help you out in the long run. then check throttle cables and IAC valve

 

Thank you. I'll check on that as soon as possible. I hope its not the throttle body. I recently replaced that when the rpms were jumping. I forgot to mentioned that on my main post.

 

I had the same problem with our 2002 Elantra. It turned out to be a bad gasket on the intake manifold. What would happen, as air leaked past the gasket the RPMs would drop, then the engine would try to increase the RPMs back to normal. I would get this up and down running engine.

 

all said and done i feel definitely is not the throttle body..so be rest assured..

 

Sounds like a large intake leak. Obtain a spray can of carburetor cleaner. start the engine and open the hood. aim the spray where the manifold meets the cylinder head and spray. if the engine goes crazy you've got an intake manifold gasket that is leaking. you may hear a "sucking sound" just like Ross Perot did about NAFTA. aim the spray at wherever the sound is coming from. btw that dude shouldn't be called a "mechanic" if he doesn't do it "professionally." I'm not trying to be mean but calling him a mechanic gives me a bad name...

 

yes. no doubt its a vacuum leak