Good compression and all. What can cause a miss? Intermittently at that. When you first start the truck it runs fine on high idle but as soon as it comes back down less than 1000 rpm it starts this intermittent miss.

1988 f150 4.9l
185k miles

 

Did you check the spark plugs and wires? Cap and rotor?

 

x2

 

Sounds like an intake vacuum leak to me.

 

Yes. All new plugs, wires, cap, rotor, distributor, and coil

 

Haven't thought of an intake vacuum leak. And I removed the air pump. Would that affect this at all?

 

Air pump won't affect how it runs. I would run the engine and spray some carb cleaner around the vacuum lines, around the throttle body and intake gaskets. Hold 1 hand on the intake to feel the stumble, if the idle changes where you sprayed it thats where you're leak is.

 

Oh I've done all that. No vacuum leaks that I can find. Sprayed everything vacuum with Carb cleaner and no leaks

 

Did you pull codes yet? If the stumble is only at idle I would also check/clean you're IAC valve.

 

Only code I've got is 34. And it isn't just at idle. Truck bogs down heavily under throttle while driving. But revs fine. Don't understand it.

Also holds steady at 22 inches of vacuum. Which also leads me to believe that no vacuum leaks are present