I have a 2001 pontiac grand am 3.4 sohc engine with 75000 mi that has lifter noise, I have replaced all roller lifters, rocker arms push rods, and still have a definate lifter ticking noise, can, t get rid of the noise not as noisey when the eng is cold 60 seconds later the noise begins, sounds like one or two lifter noise only? Thinking about changing the camshaft as last resort. Help! Any tsb's? Will gladly donate on your response, and any future questions or concerns, thanks!