I have a 98 F150 4x4. I had some trans trouble so I pulled it out and had it rebuilt. Now when it shifts into drive the rpms speed up right before it shifts. What is causing the trans to do this? It doesn't do it all the time, only if I take off faster the usually which is most of the time.

 

Based on your report, the shift function in the trans is unreliable under variable fluid pressure causing the rpm flare.
A servo, clutch pack, a valve body spring/valve may be sticking.
Your rebuilder needs to address the issue as he should know just what parts of that chain are in use for the upshift and check them out.
Any codes involving the transmission are electrical in nature as the PCM only monitors their electrical circuits and cannot tell any mechanical malfunctions beyond the solenoids operations.
Good luck.