Problems after 00 transmission rebuild

had the tranny rebuilt and a week later the check engine light came on and then the check transmisson light. The guy that rebuilt it said the check engine light was sending a code that made the check transmission light come on. so he replaced the EGR and the whole senario happened again. so he ran the code and said the map sensor needed replaced. replaced it last week and both the lights came on two days later. during this two month span it is still not always catching in R. And sometimes bucking into 2nd gear. what to do? make him double check the rebuild? let him keep running the codes and replacing whatever it says? can the check engine light really make the tranny light come on? any suggestions would be greatly appreciated!

I wouldn't keep going back to him and replacing whatever parts he says to.
I would suspect a problem with the trans.
Could also be a problem with the selector switch on the trans shifter (underneath the truck). When it goes bad you can get some strange shifting problems, or maybe it wasn't reinstalled correctly.