truck serging and hard shifting

Hey new guy here. just bought a 1995 chevy 4x4 6cyl. When it goes from 2nd to drive it gets to 3k rpm and then sometimes it serges. Put seafoam in and was thinking that it might be a bad tran filter. Yuch have to drop exhaust to get pan out. any thoughts..

It could be a sticking valve in the valve body, but, before you get too involved with the transmission, check the fuel filter, fuel pressure, and the leakdown rate. Ignition in RUN position, engine cold & off, fuel pump running: Must be 60psi to 66psi. Must remain above 55psi for 3 to 5 minutes after the fuel pump shuts off. Post your findings.