In my first attempt at a throttle upgrade I got a bad throttle body which exhibited the problems you are both having. I got another throttle body and that corrected the problem. Throttle bodies do go bad.
Here is the throttle reset procedure. It won't hurt to give it a try:

Keep the key in for the entire process.

1) Turn the key to the on position, the position just before the starter turns over.

2) Press the gas pedal firmly to the floor with the key in the "on" position.

3) Hold the pedal to the floor for five seconds, then turn the key back to the "off" position (don't remove the key), then release the gas pedal.

4) Wait 2 mins. for a full reset

Summary: Key on, pedal down 5 sec, key off, pedal up, wait 2 minutes.


If this doesn't work, disconnect your neg. battery cable for 20 minutes.
This will re-set the parameters in the drive-by-wire