Okay, I got in my 02 CLS this morning and started driving down the road. It was bucking a little but I thought it was just cold. Well when I put it in park, the RPMs start going crazy, like from 1k up to 2500 and back down again. And it keeps doing this over and over!!! Anyone have any idea what is going on?? I'm scared to drive it at this point.

Thanks

 

I think thats the Idle Air Control valve (IAC)...take it to the dealer, it shouldn't take more than an hour to fix!!!

 

itll happen from any vacuum leak ...i have too much experience there...the IAC is the first place to look

 

yup vacuum leak. this happened when i didn't put my intake on all the way and started the engine