I have a 1991 legacy wagon. It's been losing power over the last few months. I have to step on the gas pedal very lightly in order to get it to move. If I step on it too hard, the car just laughs at me and doesn't move. I was in a left turn lane the other day (this is the worst incident) and when the light turned green, I barely touched the gas pedal and the car would not crawl more than a couple inches (perhaps that was just the tranny propelling the car forward). I couldn't push the gas lightly, hard, or anywhere in between. I couldn't even rev up the car. It had nothing to give me. Rather than crawl and get stuck in the intersection, I left it there. Husband rescued it 20-30 minutes later and was able to drive it home. I don't know if turning off the car somehow restored some power or if the problem went away. The check engine light came on about a mile or two before I got to that turn lane and stayed on. After exiting the freeway the other day, the check engine light came on, but then turned off almost immediately. The car does not like going up hills either. I have to step on the gas pedal very lightly to get it to down shift.
We tried to read codes unsuccessfully, but will try again. We took off the muffler and catalytic converter, which made no difference in power. I've searched the internet far and wide, with dozens of possible causes coming up. (Of course, I didn't come across any stories very similar to my own.) I'd really like to narrow it down. This is hesitation like I've never heard of or experienced before.