Suspect is a 88 F-250 with a 5.8L engine. It has shorty headers and Taylor spark plug wires, both fairly new. Air pump removed by the PO.

Problem is when cruising at a steady speed the truck bucks, hesitates, surges, runs rough. If you press the gas pedal it goes away, runs fine. Idles fine, too.

Formerly it had a problem with stalling out when coming to a stop, but I discovered a vacuum leak at the plenum gasket, fixed this and the stalling went away. I went through the rest of the vacuum hoses, made sure everything was hooked up correctly and no leaks.

Problem happens more when the truck is warm. I replaced the ignition module and the problem went away for 2 trips, totaling about 30 miles, but suddenly started again. I have a pick-up coil to install, but haven't done so yet.

I've recently changed the fuel filter, the O2 sensor, and the spark plugs.

 

I have the same problem was gonna do the pickup coil but heard it's easier to just get a new dizzy let me know if it helps your problem

 

It didn't help at all. Only good news is it wasn't really that hard to change the pickup coil, only took about a hour to rebuild the distributor.

 

Does it do it at any steady state RPMS? For example if its in 2 gear and steady state rpms does it do it? etc...