Mazda3_driver

I was driving today just on Main Street in my town keeping a 25 mph and maintaining RPMs and my A/T light flashes on for maybe 3 seconds and then is back off. This happened 3 times today all at different spots while I was running around town. Now the cars check engine light has been on since I’ve gotten the car (I got it from a used dealership) and I’ve had everything checked and nothing can be found wrong with the car. It’s always driven fine until today. The car would jolt, A/T light comes on and the car won’t accelerate or decelerate and then 4 seconds later it’s back off. I’ve tried finding things like this but most say their check engine light comes on when it happens but I don’t know. I checked the tranny fluid levels and it’s full still from the flush the dealership did 09/29. My daughter has to start driving this car as she just got her license and I don’t want it to break down on her.