Mpjb

The car has 157k on it. It's relatively new to me so I have know idea how many miles are on the plugs.

I have a 2003 Outback H6 that hesitates and backfires when under a load. Like going up hill or passing. I'm thinking fuel filter or plugs and wires. Then I realized the car doesn't have wires, it's got the solenoid packs at each plug. The check engine light never comes on either. Anyone know what's going on? Thanks,