I've tried searching for this issue but can't find anything about it. Not sure what to call it either.

91 F150 with 302, 61k miles. I replaced the belt, cap and rotor, coil, and plug wires. Also put an electric fan on it. Cap and rotor are msd, wires are motorcraft as is coil, and I have autolite plugs to put in it soon.

Anywho, it ran okay when I bought it about a week ago but two plug wires were worn through and the belt was squealing (every little thing was original labeled 1991). After the half assed tune up it sort of "surges" on acceleration. Lots more power than it had, but it seems to go up 200 rpm, wait half a second, go up another 200 rpm. It's under light-medium throttle. If I floor it it is smooth.

I'm lost, maybe plugs will clear it up, but it doesn't seem that way. Appreciate any help

 

Check all vacuum lines, and see what happens with the new plugs.

 

No vacuum leaks, and it was missing until the penetrating oil burned off. New plugs are in, lots more power but still that weird fluctuation. Never felt anything like it

 

Seafoam. Use it. Check for DTC's. Clear codes. If the vehicle sat a lot your fuel filter may be full of garbage. Even if you changed it already check it. Pull the rear line off the filter and let it drain into a pan. If you see anything but clean gas drain out change it.

 

Used seafoam the day I got, should have mentioned that. Okay so I'm pretty sure I got the codes, only did KOEO for right now.
11-11-11
327-328-327-328