E4OD tranny really weak when cold

Sooo, I'm betting this question has been asked and answered on the forum somewhere, but I couldn't think of any search terms that gave me an answer. Anyway, when I'm parked overnight on a hill and try to drive off (and uphill) in the morning basically nothing happens. Or almost nothing, because the engine revs and the truck does actually start inching up. If the hill is very steep, I have had to roll back down and take a running start at it. I know the trannies on these trucks are lame, but I'm hoping that I'm not looking at a high dollar repair. I checked the fluid level and that wasn't the problem - any thoughts would be most appreciated. Cheers, Lock