I have a 91 F-150 with the 300 6-cyl. Recently changed plugs and wires. Idles fine, accelerates fine, but at any cruise speed it seems like the engine misses or cuts out, intermittently. Sometimes worse than others. I suspect fuel filter, or weak fuel pump. Any other ideas before I start experimenting? Thanks

 

Sounds like an air,spark, or fuel problem.

Id start with a fuel filter, and also test your fuel pump for correct pressure.