1999 legacy gt

It THINKS the automatic transmission fluid is overheated, so it reduces engine power to protect the transmission. Likely bad AT Temp sensor or damaged wiring.

With it being a '99, it could be a corroded wire in the MAF (mass air flow sensor) that is in the intake ductwork after the air cleaner housing. They are pricey, like $250 (obviously not the much higher price from the dealer) for my old '92 Legacy. The maintenance schedule in the owner manual might not even mention the MAF sensor. Some take the stance that you replace it when it fails; however, the gradual corroding means your engine becomes progressively richer. You could just hose it off yearly with some MAF cleaner to keep it clean[er].

You want to get some MAF cleaner spray to clean the heater wires (the air flow over them cools the wires to change their resistance so that's how the MAF sensor detects how much air is flowing past it). If just spraying doesn't work, c-a-r-e-f-u-l-l-y use an ear swab soaked with the cleaner to rub on the wire to clean it.

That's the problem that I had (with a '92). The MAF sensor wasn't working so it would enrich the fuel so much that it would flood it. Trying to keep it running meant pushing the accelerator pedal to keep RPMs over 2000. It had no "pull" when I would try to take off from a stop and instead wanted to die from getting too much fuel. I had to sit at a stop with one foot on the brake and the other pushing the accelerator pedal, and then when I got a green light would have to rev up the engine even more to have some power to pull away from the stop.

Pull the codes from the OBD2. If it is a MAF sensor problm it WILL have a code for it. On 1992 you didn't have OBD2 so problems like that could hide in plain sight - not possible on a 1999.

what he said, And the MAF isn't related to the transmission anyway.

GW