My car is doing something weird with the RPMs. When I start it, the revs are fine. But after I drive and come to a stoplight or something, the revs jump between 2000 and 2500 rpm at idle. When I turn the wheel, the revs go down a bit but still are high. And also there's a strange humming sound during this whole process.

One of my friends thinks it might be the alternator. I'm going to have my mechanic take a look at it and see if he can figure it out.

Anyone know what might be causing this?
Thanks

 

problem: you're too much of a throttle freak

 

Alternator? No. Alternator doesn't regulate your rpms. As for what it could be...I am not sure.