jell

I have been having difficulty troubleshooting the transmission. It won't go into any gear but neutral or reverse very easily. Dropped trans pan and valve body thinking it was the O/D servo ring but it was fine, so replaced filter, gaskets (upper and lower valve body), and fluid (small amount of metal shavings on magnet and ATF was clean). Next I replaced the OSS sensor and that has allowed it to shift when you bring RPM's up to around 2,000ish and patiently wait for it to shift into Drive with or without O/D on (not hard shifting fairly smooth). Next I am going to check OSS wiring for continuity (assuming I can figure out where other end of wires lead) and look for the grounds (don't know how many there are or where they are or which one(s) pertain to this issue) and see if they need cleaning/repair also add another ground from negative terminal to block since it only grounds to the firewall, right now. I have read various threads were people state they have two grounds from negative terminal. I am the second owner to this vehicle, first owner added after market camera, DVD player/stereo and I am not sure of what else which has lead me to exploring grounding issues as well as looking at the wiring from the OSS(not to mention it relates to the error code). If I had the service manual(s) it would make it easier I believe to troubleshoot/repair this issue(not exactly earth shattering statement!) but how many are there and which one(s) is/are needed for this issue?