I have a 1992 F-150 with 5.8L. It has started to idle a little rough and when i get to around 45mph it will develop a misfire. If I give it gas, the misfire goes away. The check engine light will come on periodically but then shuts off by itself after a couple of minutes. I have changed the plugs, wires, cap, rotor, air filter, and fuel filter. I was wondering if it could be an O2 sensor problem or if anyone has any ideas. If it is an O2 sensor, I only find 1 before the converter...is that correct. Any help would be appreciated.

 

I am pulling my hair out on this one. Does anyone have any suggestions?