What causes the transmission to not shift from 3 to 4

What is your question?

Just become owner ,have checked relays and fuses.Have also been checking wiring .I believe it is in limp mode because i have seen the message no speed over 90 flash 2 times .I also have checked codes PCM p0102,p0753,p1645 and ipc u1000 still current ,any information would be greatly appreciated ,thank you.

What makes this problem better or worse?

Seems to have misfire sometimes