I have a problem of a fuel restriction and when i go on extended drives the car will run leaner and leaner until it dies and it also dies when i gun it after a little while of driving. Does your car actually die? If it won't go over 60 or 70 (which is real bad) then it would be understandable for the problem to occur under acceleration. Does your car lack alot of power as well? Have you checked your timing -initial and mechanical/vacuum advance- , if it's retarded enough (if the advance mechanisms don't work) especially if the advance springs in the distributor don't work or the vacuum advance diaphram has a leak the car will hit a certain rpm/load and then be gutless. You can check with an adjustable advance timing light how much timing you have. Have someone rev your car to 2500 rpm and adjust the light until the mark hits 0* (i believe) and you should have around 30* of timing at least. Good luck!
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'84 Mustang 5.0 LX
My car