1993 Mercury Villager Runs rough after engine warms up

The vehicle runs great until it warms up, this is driving or idling in driveway. About 20 minutes. Then it begins to run very rough to the point of barely being driveable. I have replaced, plugs, wires, cleaned that disc in the distrubtor, replaced the engine temp sensor, still does it after it warms, I've yet to even hear the radiator fan kick in because it never gets hot enough to kick it on. I unplugged the MAF, it will barely idle but will run after warm, not even close to driveable though, if I plug it in again it immeditately goes dead. Can't tell if that's related since not a very big difference.