Subaru Repair: outback shutting off, outback wagon, subaru dealer

Question
I have a 98 Outback wagon and when driving sometimes when I slow down my car will shut off or chug like it doesn't want to go.  I keep up on my oil changes and maintence.  When I took it in to the Subaru dealer thay ran dignostics and nothing came back it.  When this is happening my check engine light comes on, I can shut off the car then restart and light is off and everything is OK.  Please advise what this could be.
Thanks,  

Answer
When the check engine light comes on, do other lights come on too? I think when the light comes on, it is because the key is in the on position and the car is not running, kind of like when you turn the key on, but don't crank the car, the dash warning lights turn on as part of a bulb check. If I am right, that would explain why the dealer couldn't find any codes - because the light did not come on as a failure indicator, but as a bulb check.

As far as your problem goes, do you have any other problems? How often does this happen? This may be something you will have to let a mechanic drive for a few days, so they can experience your problem.

At this point, my only guess might be a gear in the transmission at the speed sensor - but that is just a wild guess. Normally, there is a speedometer issue or speed sensor codes.

Good luck.