This was the collective effort of three separate shops and we all agree that the transmission overhaul was probably unnecessary at the moment, but not outrageous, considering the mileage. The car would balk going up hills, but ran fine the rest of the time. One mechanic kept it for three days and said he was convinced that the lockup clutch was dropping out intermittently. He had his diagnostic tool connected the entire time and it didn't show any problems. He sent us to a transmission shop we'd dealt with before and they reached the same conclusion. He told me that, if he took the transmission apart, he'd totally rebuild it, which we agreed to. He also replaced a motor mount that was disintegrating. The problem returned within a week and the check engine light came on while en route to the transmission shop. He put the diagnostic tool on it again and it showed two plugs had misfired ~600 times. Both were on the same ignition module. He sent us to a nearby shop to have the module replaced and that fellow showed me the ignition wires should be replaced as well. That probably would have fixed the problem in the first place, but I can see how they missed it. 600-misfires in 60-miles to the shop is a very low %.