Thanks for the input and excellent advice! I picked up a new TSS because the dealer was on the way home and it was a cheap enough 'guess' to try out. I'll swap that out tonight, do a tranny flush and then get as many codes out of the OBD1 as I can and pick up a range sensor tomorrow if the tranny is still misbehaving. After about 15 minutes of driving the trannny behaves completely normal.
I'll post any significant updates. Thanks again!
