Hey FunkNuggets,
That sounds like a nightmare much like mine was...so far it's still doing pretty good. I had my tranny rebuilt and was still having issues. Mine was a process of elimination deal, and it seemed to take forever. When it was said and done...make sure that your transmission is a-ok. If it's good, then make sure that they check the flippin' solenoids and make sure they aren't bad (like they SAID the did on mine). If everything is good...it may very well be an electrical issue. Mine didn't go into R when shifting from N. The shop I took it to didn't charge too much to test the electrical system to diagnose the issue....but thank God it wasn't the wiring harness or somesuch...because it's an expensive issue....between $2-$5K. I hope this helps you some...I can definitely relate to the frustration.
My check engine light is on right now, but I know it's because if my CO2 sensors. And now my brake light. I tell you what...it seems to be one issue after another with this car....but I still like it....don't know why.