07pt runs rough sometimes

I have an 07 PT with 35000 miles on it. It had the head gasket replaced last fall under warrenty. Now it on ocassion will start and run rough. I mean really rough. It's on the verge of stalling. It drives ok but when it idles it runs rough it shakes the whole car.
this happens about one every two weeks. and then it's fine. No codes. Any thoughts'

Jim

I have an 07 PT with 35000 miles on it. It had the head gasket replaced last fall under warrenty. Now it on ocassion will start and run rough. I mean really rough. It's on the verge of stalling. It drives ok but when it idles it runs rough it shakes the whole car.
this happens about one every two weeks. and then it's fine. No codes. Any thoughts'

Jim

Bad gas, check your spark plugs and the fuel filter, maybe look under where the head gasket is, and check to see if there is any build-up due to someone spiking your gas with something else-black residue or gunk.