Wondering if you got anywhere with the issue? My 02 WRX was doing the same thing, and I found it was the speed sensor. My crank sensor went out in the midst of a '06 LGT trans swap. I fixed it and then realized that we never put the speed sensor in the new trans and my car was in a sort of "limp mode." Unhook the battery and take it for a spin...see if you can rev normally. Vss replacement whenever you can, its a pain, but I have to do it too! Good luck!