I have an 88 F250, 302 Fuel injected 5-speed that runs great... Most of the time. Every once in a while it wont idle, what could cause sporadic idling problems? Also when going up a hill it loses power, and will begin to shudder. This rough running will sometimes take a couple minutes to correct. What could be causing this? This also happens when towing say a boat on a flat road at a sustained speed. Any help would be great.