engine missing question

[woodrat]

so, last night, between stopping at the grocery store and leaving again, my subaru developed and engine miss. It sounded like a loose plug wire, but all was tight there. It smooths out and runs decent about 3k RPM, but at lower engine speeds and especially under load, it sounds like it is not running on all four.

I managed to drive it 100 miles last night like that and it never overheated or acted strange in any other way except a little worse mileage. I'm not all the way home yet, will be later today, but I ma wondering if someone can point me in the right direction. I'm thinking it might be the coil, but I have no expereince with distributor-free ignition systems. Any advice? I'm probably at about 20k on these spark plugs, so I think I will try to pick up some new ones before I get home. NGK, right?

thanks

[SLODRIVE]

A good place to start would be to pull the plug wires off of the spark plugs. If any moisture gets trapped under the boot, it can easily short the wire out and cause a nasty miss that can come and go.

I bought my previous Legacy for $500 partially due to a miss much like you described...10 minutes after I got it home, I found the above problem, blew out the area around the plug as well as the boot, and all was well.

[92ss satinsvoice]

i would also add, when's the last time you replaced the wires or plugs?

[woodrat]

Well, i went to put new plugs in , and the #3 hole is stripped. Plug is still kind of stuck in there, but I'm guessing that is the source of my problem. I bought this engine about 17k miles ago, and it had been rebuilt 80k previously and recently tuned up so when I dropped it in, I didn't do anything with the plugs. Now I get to go to the parts store and get a helicoil kit. I would rather have done that while the engine was sitting on the back of my truck than now.