[mickeykreg]

Mine was doing almost the exact same thing on a recent trip from here up through Montana and Idaho and back. I ran one of the tanks outta gas and it started running bad, and getting progressively worse. Changing the fuel filter fixed my problem.
It's not vapor-locking when your heating while climbing the passes?
One of the heater hoses didn't relax and settle on the fuel line?

Bummed to hear of your predicament...I can relate.