I have an 04 GMC sierra 1500 with a 5.3, just hit 85,000 miles and just replaced the heads cause of the castech issue. The light would come on periodically before the head change. Also noticed poor fuel milage and throttle response. The P0101 code comes on when accelerating and goes off after been sitting a few hours. Should I Just replace the MAF sensor. It has a cold air intake on it. should i get a tuned MAF sensor? Thanks in advance