What is the problem when your car keeps misfiring, then a service light comes on

What is your question?

I have had it to the chevy dealership and they put it on their machine and can't seem to come up with what is exactly wrong with it. Have fixed different things and it continues to do it. Also as driving will hesitate like maybe you have gotten some bad gas and eventually the engine light comes on and I take it in again. I bought this brand new and I am the only person driving it and am not hard on it. I do have 202,000 miles on it. The last time they did a fuel flush top engine cleaner from GM. They said they next step could be looking at new valves or a head. So maybe I should be looking for a different vehicle, as that is my only transportation.

What makes this problem better or worse?

I doesn't make any difference if the engine is warm or cold.

How long has your 2012 Chevrolet Malibu had this problem?

It has been doing this for about 3 years.