1993 K1500 4l60e Tranny Problem

[gjoakum]

hey guys i am having an issue with my 4l60e tranny that i hope someone on here could help me with. little info on the truck first. 93 k1500 ,350.. just recently put in a used transfer case. changed filter and fluid in tranny(wasn't burnt) replaced speed sensor. fuel filter, fuel pump. fuel relay. changed fluid in rear. i used my obd1 code reader and also just to be sure used a paper clip and i am getting no codes except the normal 12 code. the issue that the truck is having is there is a dead spot in the rpm anywhere from 900-1500 rpm nothing happens. and as soon as the truck gets past 1500 it will then kinda jolt. i first noticed it when towing my stepmothers car with a tow dolly. i was going down a hill and went to shift from Drive into 2nd and when i did nothing happened until i hit the throttle and knocked the rpm's above 1500 then it kicked in. my first thought was that i had completely lost 2nd gear. but then i noticed it doesn't matter what gear.. i am really confused as to what this issue is and i was having trouble searching it. hopefully someone will understand my problem and can possibly help me with it.