I have a 91 F150 4x4 with the 5.0 and standard.
It has a low mileage overhauled engine. The truck is all pretty much stock.
Still computer controlled.
Is there a cam that would give me better preformance?
I take it in the mud often.

 

The issue with getting a cam is you have speed density on your truck. The computer might not like an aftermarket unit. You might consider some gt40 heads off an explorer/mountaineer. If you're just increasing the air flow the stock computer doesn't mind as much as if you change the operation of the valves.