Re: any ideas?
Have you done a compression check? Your cyclinder pressures should all be within 75% of each other. Loss of compression would explain loss of power on an incline.
Possible explainations for loss of compression are rings, valves, seats, or maybe even a cam lobe (which would make the vehicle run rough, so probably not your problem).
Question: Does your engine run a little rough, then smooth, then back to rough on occassion? If so, suspect needing a valve job.