I have awith 2000 Subaru outback with about 155k miles. Awhile back my check engine light came on so I took it to autozone and they said it was a cylinder 3 misfire and it was probably a clogged injector. I put some seafoam in and the code eventually cleared and it was running fine. I drove it about another 1000 miles and got in it one day and noticed it was running rough and the CEL came back on. I took it back to autozone and they said the same thing... the light started blinking which I found out is an active misfire... I replaced the plugs and wires and put in a new coil bit it was running the same so I put the old one back in... the car is running worse every day and I noticed the other day when I shift or push the clutch in to stop the Rpm goes down almost to 0 until I completely stop then it goes back up to about 6 or 7 hundred. It idles rough and is a little low on power. I asked the dealer I bought it from if they changed the timing belt and they said it looked like it had been replaced at about 100k. There was some oil on the plugs in cylinder 3 & 4 (I think... its the two in the back) but it wasnt on the spark part only the porcelain. Any help would be greatly appreciated.

these cars don't do well with anything other than stock NGK plugs and Subaru wires. as long as the wires were higher quality stuff they should be fine but in some ways there's no way to tell unless you get OEM.

 

i have seen wires right out of the box cause cylinder misfires that made the vehicle nearly undrivable - it's an EJ engine thing. older subaru's would run on coat hangers for spark plug wires. LOL

 

the igniter could be bad as well. (which cylinder misfire codes are you currently gettins - which numbers?)

 

i had a cylinder misfire that went away when i swapped an entire intake manifold so i assume that means it was fuel supply/injector related.

Check the harmonic balancer. Sometimes they loosen and when they do they throw misfire codes. Mine started with 304 then went to 303&304 then all 4 before I figured it out following a tip on this forum. I ground i thread off the bolt and threw a new balancer on(the keyway on the old one was gnarled) and problem solved.