l have the same year and model car, with the exact same symptoms.l replaced the spark plugs and the misfiring went away for a week, but is now back to the same issue.Where is the MAF located, so l can check that out before changing the wires and the ignition coil?

unless you changed the intake to a cold air your MAF shouldnt be doing anything.


Best bet is the ignition coil. Prob because of age bro.

Before u waste thousands of dollars being a parts changer, isolate the problem & condition first before u replace good parts. Subaru is can surge in power due to many other things. If ur MAF is failing u would get a check engine light due to an intermittent EF l problem. If ur coil packs were failing, it would also cause a check engine light from varying ohms in resistance in the pack.
Surge in power, runs rough, search for a vacuum leak first before u replace the engine.

l am pretty sure ur RS uses a MAP not a MAF. Like the guy above said, just go through & check things out. If u r not getting a flashing CEL light, u r not misfiring. Make sure all ur vacuum hoses r on correctly. Also make sure ur fuel filter is in good condition. Spark plugs & wires should be checked too. If there is a misfire code & it is isolated to one or two cylinders, then move spark plugs & wires around. For example, of cyl 1 is misfiring, switch spark plugs between 1 & 3. If 3 starts misfiring, then that was the problem. If not then switch plug wires. So on & so on. u get the idea. Good luck with that. l had misfiring problems once & t was a headache & it ended up being a bad injector.