Start car, RPM's gradually increase, put in.

I would take a look at the throttle position snesor or the speed sensor. They may not have come up in scans but they may not be out of spec yet to throw a code. You might consider mechanical issues that is making this happen. Look at the intake butterfly valve and make sure it and the throttle cable anre moving freely and can close completely.
There may be some carbon buildup on the itnake at the valve keeping it from closing all the way that needs cleaning off. Or the throttle cable may be getting stuck. You can also try putting your foot under the acceleratopr under pulling the pedal up. Always remember that you have to take it out of gear, or you must have a way to slow the acceleration down, to slow the car down. Taking out of gear is risky though as it may cuase transmission damage. But that is better than out of control acceleration.