I have a 92 grand prix with the 3.1L V6 multiport. The whole fuel system has been replaced except some of the lines. The issue I am having is the car has no power going up hill in drive and no power in reverse. Everything else works well. The car used to run better before this issue, but it is manageable to go flat or downhill. Also, the car revs fine in neutral and park. I checked the gas pressure in the block and it read anywhere between 36 and 44. I am out of guesses can someone please help?