legacycentral bbs

I have a '92 FWD NA Legacy with the 4EAT. It's usually a pretty peppy little car, but starting this afternoon it has been having strange acceleration problems. The car starts fine, and accelerates normally to about 20 MPH. There it's as if the engine just loses power. It gets a little better as the car warms up more, but even after 10 minutes of driving, I can't get the car to go much faster than 40 - 50 MPH. During this whole time the tach never climbs above about 3000 RPM, even if I floor it to engage "power mode." There's no check engine code, and the only code I get from the tranny diagnostic is from the "previous problem" test, and it's a code 32, "Vehicle Speed Sensor 1." Any ideas on what the problem is?