2004 Ford Focus transmission/coolant light comes on and car bumps and turns off at any speed

It’s a Ztec engine with 150k miles. At any speed from 30 to 65, this car will suddenly bump hard, engine stops running, transmission/coolant warning light comes on for about 3 to 5 seconds (as does the small red light next to the hazard warning button), and then starts up again with a touch to the accelerator pedal. This happens occasionally when I touch the brake pedal OR when I use the turn signal.

I had the transmission fluid and filter replaced and went 5000 miles with no trouble, but this same problem has returned…same symptoms as before.

Any suggestions?
Thanks for any replies.
johnt