Evaporative problem, I think
I have a 92 f-150 with the 351. Lately, the idle has been slightly rough. I also seem to be getting worse gas mileage than usual (hard to believe). When the truck is towing, it seems to have power pulsations. Also, if I pound on it, it will pop when it reaches high rpms. It seems like it is running too rich. The plugs, wires, and distributor cap are all new. I also got an evap system code when it was tested. I'm not sure exactly what part of the evap system would cause this. I have already looked for cracked or disconnected vac lines with no luck. It tends to do this more once the engine is warmed up.
Thanks for your help,
Scott


