Welcome to AF and sorry for the late reply!!
First I'd find & fix that vacuum leak, could be causing your troubles.
Also had the car been sitting for a long time and not driven ??
If so, I'd try a fluid & filter change to see if that helps.
I'll see if I can find this link to a transmission site with testing procedures so you can test the TCC, it to might be the culprit. You might need to take it to a trans shop and let them scan it for codes.
Found these two links that might help.
http://www.atraonline.com/manuals/ge.../tetdv-c3g.htm
http://autorepair.about.com/cs/doity.../aa011703a.htm
Hope that helps !