300GE Performance Problem

[tetekale]

I have a 1990 300GE. Taking off from a dead stop the truck chokes, struggles to pick up speed but once it gets going it seems to be fine until I come to a stop and have to take off again. If I am on even a small hill it is almost impossible to take off sometimes I have to engage the low 4x4 to move along, and it gets worst if I have the A/C on. Standing still if I floor the accelerator it misses and sometimes backfires. I have either replaced (new) or tried the following parts from another 300GE in good running condition:both fuel pumps, fuel accumulator, fuel distributor and fuel pressure differential attched to it, injectors, fuel pressure regulator at return line, crank position sensor, coolant sensor, ignition module, ignition coil and wires, distributor cap and rotor, electronic control module but to no avail. I don't know what else to do. At this point I am thinking about a switch to diesel engine. Any help will be appreciated.

Thank you