Calibration is, or may be, only half the issue. That was the case for me anyhow.
You should spend some time on the calibration screen slamming your foot on and off the petal like you do in a game. Note the value it starts at and where it ends up as you slam down the petal and release it quickly. (The values are in HEX)
While calibration solved the issue for the most part I was still having the issue occasionally. What I found was going on was the POT was bad/had a bad spot and sometimes the release resulted in the thing reading fully depressed. I had to pull the pedals and reset the mechanical action to use a different section of sweep on the POT. In particular I had to use the upper section, from the upper limit (FF hex) fully depressed down to the mid range when released. This was because the previous setting was from the lower limit up, which is easier mechanically to setup and this was now worn out.