Opened gas cap while car was on..

Went to the gas station and opened the gas cap while car was on and pressure released from the gas cap.. ever since the. The engine won’t go to idol when using the electric motor, and when I come to a stop the engine switches on and off, messing up the mileage I could be saving from using electric… I switch the mass air sensor and the check engine light went off but the car ain’t running the same. Is it a quick fix, and does it have anything to do with the pressure in the engine itself?