1990 Subaru Other

My 1990 legacy misses, I have improved this by using higher octane fuel but the problem still persists. I think the coil packs are failing, is there an additive/treatment I can use that might reduce this problem?
December 8, 2006.

When does the engine miss? At idle speed or when driving? At idle speed it coould be spark plugs or wires a vacuum leak or incorrect timing.
If it does it while driving it could be the fuel filter spark plug gap, incorrect timing or a cracked coil.

Feb 26, 2007.
The coil pack on a 90 legacy almost never fails.I would look at plugs and plug wires first. Second, If the vehicle has an auto trans.I would suspect injector failure The 90 to 91 legacy 2.2l( auto trans only) has a known injector issue. Not really sure if the later is a a good job to try your self though.

Feb 27, 2007.