Will not Move unless given excess throttle

Okay I have the vehicle listed above Sierra with the 350 and the 700r4. When I had gotten the truck transmission only had 1 and 2 gear but ran and drove fine. Then one day when I was driving it jumped time so I said okay I'll swap transmission as well. I redid the timing and no issues, then I went and swapped the transmission and issues aroused. It would start but when put in gear it'd take about four seconds and would stall out. So I would give it a little gas so it wouldn't shut off but it wouldn't move. So I gave it more and more and finally it moved but at all crawl and I was at about 60-70% throttle. So I asked so Mechanic and he told me it was the TCC solenoid. I replaced it and now it doesn't stall but it still won't go without giving way too much throttle. I'm stumped and I need help.