itr.#1446

Recently developed a problem with my trans after pulling some friends out of mud that they were stuck in. Truck will not want to shift out of first unless i let off the gas then it will shift to second, but if im going up a hill and going to slow it will go right to first and not shift to second no matter how hard i try to. Fluid level is good all other gears are fine, i installed a trans go shift kit last year and was wondering if that may be the problem. I never like it since i installed it so i was thinking of ordering a new valve body and checking the bands while im in there. If anyone knows what my problem is let me know i need to get my truck back up and running!