My 94 F250 (5.8L, C-6 auto 4x4) has been started running Eratic again. I was comming home earlier today runing about 65 mph on the highway. My check engine light came on, stayed on for about 10 seconds then went out. 20 seconds later, it came back on again. It did this cycle 4-5 times. Truck was running ok, all gauges good, no smells or smoke or noise. When I got off and sitting at the off ramp waiting for the light, It was holding between 1100-1500 rpms. As the rpms, tired to drop, the volt gauge when down and then jumped back up. The rpms, jumped back up and the truck would not return to normal idle speed. Sometimes, when I woulld get off the gas, the rpms would stay the same as if cruise control was on. The truck is an xl trim and DOES Not have cruise. Brought it home, Checked all the fluids and everything was good. Oil, ok. Tranny fluid ok and not burnt to the smell. Coolant ok. Truck had the same problem back in July. I had the check engine light scanned but it didnt throw any codes out. The truck did the same thing for 3 days or so then that was it. It was fine till the end of October when it started running a bit rough again. I bought a newer truck since so this don't get driven as much but I do use it a few times a week as more of a personal truck. Truck has 101k on it and has had the following done recently. November 06 new plugs, cap and rotor and Air filter. Feb 07 All new freeze plugs, coolant flush and new thermostat June 07 New HD Alternator and serpentine belt Jan 08 New Battery I'm thinking it may be a dirty/bad PCV valve but I'm not sure. Any ideas or suggestions??