I've had my fair share of transmission trouble throughout my life, but this is my first 4x4.
Anyway, my truck runs wonderfully other than shifting into 3rd, but only at certain RPMs and only after, it seems, the transmission has warmed up. First thing in the morning, whether it be 29⁰ or -17⁰ the transmission shifts nicely and firmly, as it should. But after warming a bit, I sometimes get surging at the top of 1st but will shift nicely if I reduce throttle. From 2nd to 3rd, there's moderate power but if the throttle isn't 'perfect' it won't shift. Zero complaints with 4Hi and 4Lo. I'm hoping I don't need to replace transmission. (Full disclosure: After buying, transmission was slipping/surging with low power, noticed thin-debris-ridden fluid on trans dip, got under it and noticed most of the tranny pan bolts were only finger tight. Dropped pan, replaced o ring, gasket, filter and missing fluid, reassembled and original concern was fixed but the Trans still isn't where it should be