i really wish i knew what to tell ya. i have a 92' f-150 supercab 4x4. i really love the truck, but its been giving the same trouble. i changed all the same stuff you have. i took it to 2 different machanics. all that they wanted to do was change the same stuff again. i have noticed that mine doesn't pull back or hesitate quite as bad if i have overdrive off. it may be because engine is running at higher rpm. not sure. i dont think it is in fuel system. i have dual tanks also. i havn't had any touble with fuel transfering between tanks. it feels like missfire of some kind, i just cant track it down. i have the 351, 5.8 with automatic e4od tranny. i thought maybe it was a vaccum leak, but if it is i can't find it. there seem to be a lot of knowlegable folks here, maybe some one can give us the answers we need. good luck, God bless.