Tranny rebuild no good?

[SVXtacy]

What's up guys. I just finished rebuilding my tranny, but it seems as though I'm still having issues. Occassionally, at low rpms, it'll shift hard, and the car shifts from 3rd to 4th a lot when cruising. You think that transmission AOD thing smallcar sells would fix this? This is my first automatic car. I miss my 3rd pedal Do you think the ecutune stage 1 upgrade I installed is the cause of this at all? Also, I used Mobile 1 synthetic ATF. Is it bad for the tranny to use something not so thick? Thanks guys.