A problem has developed with our 1996 Legacy Outback, and I'm hoping you folks can help me narrow down the problem before I take it in for service again. The symptoms are that in the morning, when the car is still relatively cold, it will lose power during acceleration (like when getting on the freeway). Sometimes it will be so bad as to stall out, and I'll need to pull over and wait for a couple minutes before starting the engine again. After that, it seems to be ok. Oftentimes, the "check engine" light will come on for a few minutes or hours, then go off again.
This problem started last fall. It happened a few times before the check engine light came on. The first time that happened, I took it to a local repair shop. They put it on the computer and read the code -- misfire on #3 and 4 cylinders. The mechanic did a maintenance tune-up (which included replacing the plug wire set, plugs, fuel filter, oil and filter, fluids, top radiator hose, antifreeze, carb cleaner).
The problem might have gone away for a couple weeks, but it came back. It was time for the 90K mile service anyway, so I took it back to the mechanic a few months later. He read the codes from the check engine light again, and found the same thing -- misfire on #3 and 4 cylinders. He did the 90K servicing, but didn't find anything new about the problem.
The problem continued for awhile, then went away for a couple months. It's been a bit warmer lately, so that may have had something to do with it. This week was a little colder and rainy, and the problem hit again yesterday. It lost power and stalled out, but this time it was while I was decelerating, coming up to a stop light. Otherwise the same symptoms, and the check engine light is on again.
I need to get this fixed! I don't know much about car engines, but I've got the Chilton's manual and I'm fairly handy. I'm hoping someone can either suggest some things I can try on my own to isolate or repair the problem, or else give me some ideas to bring to the repair shop so that I'm not hit with a high troubleshooting bill. Any help is appreciated. Thanks!