Title says it all. What should I do to fix this?

Try each of these in order until they work again.

• Restart LFS
  
• Re-plug your pedals/wheel
  
• Restart your PC
  
• Re-calibrate your pedals in your profiler or in the USB Game Controllers window (Start > Control Panel > Setup USB Game Controllers)
  

If they still refuse to work properly, reinstall the driver software.

I've tried all of the above steps including reinstalling the driver software (apparently just the xbox 360 accessories software)and LFS still thinks it's slightly depressed. With American Truck and Euro Truck Sim, I can at least configure the dead zones to compensate for the gas pedal being a little bit down, but I can't in LFS.

In that case, I recommend you either clean your pedals out (if that's a simple job) or use DXTweak to adjust the deadzones.

DXTweak 2: http://www.derekspearedesigns.com/download/DXTweak2.exe

Quote from gigapouch :

With American Truck and Euro Truck Sim, I can at least configure the dead zones to compensate for the gas pedal being a little bit down, but I can't in LFS.

You can, in the Axis menu you can set the range from 0 to 1000, just set it to e.g. 5-1000 or 0-995, whatever fits your case.

Ah yes, even better, I forgot that was added.

Quote from mbutcher :

In that case, I recommend you either clean your pedals out (if that's a simple job) or use DXTweak to adjust the deadzones.

DXTweak 2: http://www.derekspearedesigns.com/download/DXTweak2.exe

Tried that, but unfortunately did nothing for me except screw up the calibration and make me reset the Windows default one.

Quote from Whiskey :

You can, in the Axis menu you can set the range from 0 to 1000, just set it to e.g. 5-1000 or 0-995, whatever fits your case.

I had tried that previously, and did not work either.