The first thing I'd try is the throttle reset procedure.

1. turn key to "on" (not start)
2. push the gas pedal to the floor and hold it there
3. wait 20 seconds then turn the key off
4. wait 20 more seconds and let off the gas pedal.
5. wait for at least 2 minutes for the drive-by-wire throttle to do it's reset procedure.

I had a similar problem before......if I got in the gas normally, it felt like the car was going to stall, if I went really slow on the pedal all was fine. Did the reset procedure and all was right in the world again.

Might work, might not..........but at least it's free!