I've been running an A340F for years and on the road it isn't the best mostly because I have 4.88's and 36's. I need 5.29's and I wish the 5.71's would be trustworthy instead.
Off road I don't see the issue you are speaking off at all, even with dual cases in low low I can hold it back without stalling. Stopping on a hill has never been an issue either. I wish I could say I had a solution. Only thiing I can think of is maybe the TV cable isn't adjusted right or as a very rare possibility the TC is locking when it shouldn't.