Not sure if that is the word I am looking for but I have been helping a friend out on his 86 f150 2 wheel drive. It has the 302 and auto trans. If you give it more than half throttle it balks and chugs along but will not acelerate. This is amplified when it is loaded. Now if you use high octane fuel it lessens it but does not clear it up. We changed the fuel filter. He just put in a new pump and has plenty of pressure. The regulator apears good. There are no engine codes. The ford garage in town says "these old trucks always do things like that. There aint nothing wrong." I just refuse to believe him. My old truck was a 71 and it would outperform most newer trucks.
Any ideas? Shaun

 

When you tested the fuel pressure what was the result?

How long has it been since it had a full tune up done to it, and with quality motorcraft parts?

How many miles on the 02 sensor? (only good for 50 to 60k tops and that's in the best of conditions, extremely clean running motor).
Fuel filter change
Wires
Plugs
Cap
Rotor
any and all vacuum leaks repaired
Vac reading taken? result? 22in. Hg. steady needle? Low reading or erratic needle? both?
Base timing checked/set

No code doesn't mean there isn't anything wrong with it, far from it.

And no that ford garage is nuts, it is not normal with these old trucks if that is what they are trying to claim.
Just to stupid to figure out the problem, or to lazy to do their job. Unfortunately appears far to common a problem among ford dealerships and their service departments.