Driving in stop and go traffic at 5-15 MPH for over one hour. Traffic clears. Hit the gas, all warning lights come on and engine stalls. Restart and all is fine. Has happened a few times in last 2 years.

This time however, on restart, I have EML (Engine Computer) and transmission (gear) lights on along with check engine. Car speeds up to 10 MPH, bucks a few times, and slows down - repeatedly (safe mode?).
Shut down for 15 minutes and I can get it up to 50-60 MPH with warning lights still on. The next morning all is fine and no warning lights are on.

Has been OK for weeks now but I have noticed a few hard shifts at times.

Have never changed fluid - 140,000 miles.

Ideas?