I have 03 Forrester. Had the head gaskets replaced. It did not crank on 1st turn of the key - so I gave the gas pedal a short jab. Next crank resulted in throttle stuck and it went to full rev. It was a bit scary.
I had purchased a shop manual years ago and took a look at the diagrams of the pedal and throttle body. Turned out there are 3 clips that hold the accelerator cable. My mechanic had only attached 1 close to the throttle. So the short jab to the gas pedal had kinked the wire enough to stick in full throttle. A manual toggle of the release worked. But after reviewing the diagrams and reattaching the other 2 clips I feel better about the problem, and hope it is fixed now. Just thought I would post - since this forum got me pointed in the right direction to find the sections in the shop manual.
Your fix could also be - are all 3 clips attached in the right places? White one is close to the wall attached to the brake booster, then 2 black ones attach to hoses in the engine compartment to complete the "J" shaped curve from the pedal to the throttle body.