I'm getting a noise when I fisrt start up the engine. It sounds like rocker arms out of adjustment, could this just be carbon build up. I never accelerate heavy or even come close to flooring it. not with gas at $2.50 per gal. if it is possilby carbon build up, what do you suggest, or is rocker noise a common problem and needs to be looked at. 70.000 miles, no extended warranty, would it still be covered.