Hi GMC with 5.7 liter is having some problems with lack of power, and starting after setting a while. 110K miles. Symptoms seemed to indicate a faulty fuel pressure regulator - replaced. seemed to help only a little. Then started to loose power/accelleration and service engine soon light came on. Code 44 : Low O2 reading - replaced sensor - no change. Replaced fuel filter - helped power a lot for a week, O2 indicator still triggered after clearing codes. Replaced filter again, no change this time.
What should I look at next. seems to point towards fuel pump to me, removing tank sounds like a pain.
THanks