JP Purdom

Hey guys. I've scoured the forums for days trying to figure out if anyone else has had this problem. I dont know where else to turn. Parked my 93 Pickup (4x4, 3.0) for a week and came back to it running like garbage. The engine shakes and the whole car shakes when driving at low RPM. I have a serious loss of power and my MPG has dropped significantly. Does anyone know what this could be? I've heard all kinds of theories but figured I'd ask.

Thanks