i don't know what is wrong

sick GN

The other day i was driving my car, and it was running fine. Everything was working but ever since i got a rebuild about a month ago it didn't want to shift (1-2) under WOT. It kinda started working but not great. Then on the way home from a friends house the trans didn't want to go at all. It was like it was in neutral but it still moved enough to get home. All that is different on it is a redstripe stall. maybe 250 miles to the rebuild. I don't know what it is.

Please Help