The Brooklyn Express

When I start my car it has a slightly rough idle. (it jumps between 500 and 1000 rpm's). At times it also does this while i'm stoped at red light.

1.Can anyone give me some reasons as to why this may be?
2.And how to make it go away?

Thank! you! in! advance!...

imported_lowlife

dirty air filter ?

Nightmare

Also check your idle air bypass motor, it could be dirty