1991 Cavalier, 2.2L. I'll be driving down the road when the check engine light comes on. It stays on for maybe 1 minute or so, then turns off. It's too old for my obd2 scanner.

How can i figure out what keeps tripping the light?

 

I had the same problem on my 94 and it was the o2 sensor getting a false reading from exhaust leak but it could also be the sensor starting to go bad in your case cause it likely does it under a load once you hit hills or curvy strech in road

 

the easiest way is to get a voltage meter and back probe the sensors with a safety pin or something and with the car running they should not go over half a volt unless its its the mass air flow sensor and it should say under 5 volts if they are outside the range you found the bad sensor