I have a 84 22r and can not figure out what is causing the the truck to sputter intermittently. When diving at say 45 or 55 in 4th or 5th gear up an hill, the truck sputters and jerks. When I drop to a lower gear it works fine most of the time. When step on the clutch the engine idles fine. I replace all of the vaccum lines, tested the vaccum advance (works fine) and raise the fuel level. I replace the fuel pump, tank, filter, coil, plugs, wires, dist cap & rotor. The only thing I noticed is the clutch MC losses fluid, could a clutch probelm be causing this? If not what about a clogged EGR?

 

It sure sounds like ignition (cap, rotor, wires, or plugs) breaking down under load... But you say you replaced those. Recently? Brands used? OEM parts?

 

All were replace within less than 500 miles except for the wires. I can't remember the brands. PO replace the wires so I will get a new set.