I have a 1985 buick grand national has upgraded 65mm turbo I think, 42lb injectors. Upgraded walbro fuel pump turbo tweak chip. And has a 86-87 ecu. The issue I am having is when I first turn it on and drive it around runs great just has a little stutter under super heavy boost. Then I park it and come back to it after 20 minutes and the moment I touch the gas it stutters bad to the point where it is undriveable. Like it’s so bad it struggles to get to 10 mph. So I limp it home then the next day I go to turn it on and runs great. I’m completely lost. Checked tps it’s good, map sensor is good, vacuum lines I think are good(I followed a diagram for the vacuum lines) spark plug wires got them brand new, spark plugs are brand new and gapped to .32. Maf I checked it by unplugging it while it is running and the car dies, so I’m guessing that’s good. I’m just really lost please any help is appreciated!!!!