I guess you've tried to drive around the issue, by letting off until it locks then reapplying the throttle?
You want the TC to lock more around town I assume? Your 4th gear just might to high to work for 35 mph, as the ECU probably doesn't like 1300rpm and 25% throttle...
Also you could check to see if your car still has a throttle pressure cable to the trans. If so, you can adjust it as a way to move shift points around a bit. I'd get a FSM off ebay before playing with it though.
Also as an aid to driving around the factory trans settings, you could get a scanguage and monitor exact throttle position and rpm to see what triggers popping in and out of TC lock.