I can't drive 55

I bought a 1988 F-250 351 with ~150K miles. Ran good for several months only driving about 20-30 minutes at any one time. Then I started on a 12 hr drive. I did stop and top off gas tank after an hour but had to jump it to get it started again. The truck died two hours into the drive averaging 65 mph. I changed the fuel fiter in case that was clogged but nothing; I bought a new battery to ensure I had power to turn the engine over --it would turn over but would not start. I towed it home--replaced plugs, wires, distributor, D-cap, rotor, coil. It would start but wasn't drivable. I then changed the the in-line fuel pump--now I can drive it but it doesn't go over 55 mph and that's going downhill. It has problems getting up to that speed. The timing, from my understanding, is correct. I checked the fuel pressure--it takes two hits of the ignition switch for the pressure to get up to 40psi. I temporarily took off the catalytic converters and put on a straight pipe with a muffler--I'll be going back to the converters when I figure this problem out. Both my exhaust manifolds are cracked and anticipate to change those out too. Any ideas on fixing this speed/fuel problem would be appreciated.

Tune up, Air Filter, EGR system and re-check that timing.

ervinj

do a compression test before you spend too much money.

Thank you--maybe I should have name myself Hee-Haw. I didn't look at the air/breather filter good enough previously. Changed it and on the road again.