yesterday i got in my 06 SS non SC 2.4L and it was idling high about 1500rpm, then it dropped to like 1100rpm and bounced from 1000 to 1100 alot, jsut a lil to where you can notice the idling...im going nuts b/c im like wtf is going on! well i thought i would take it on the highway and see if it stops...i get off the first exit and slow down, the car stays at 1500rpm and is literally pulling forward with the brakes depressed...and then it drops to 1100rpm...i get back on the highway and get off my exit, it did the same thing...pulling into the driveway, same thing 1500rpm....OMG then i put it into drive and it jumps up to 3500 rpm and i just cut it off...i said screw it! i had about 3/8 of gas...well i was thinking BP gas did it! i took it to sunoco and put 93 in and drove it for a min, it was fine after that....jumped in it this morning, just fine...WIERD CRAP! anyone else?

 

Cobalts have an electricly controlled throttle. Mine jumps RPMs a little every now and then too... it's normal... nothing to freak out about.