Sounds like only one of the throttles is open hit ctrl 1+2 to open both
Its e+1+2... tap e, then 1 and 2 in quick succession. Hit shift+3 to open the throttle quadrant (in all other planes it's shift+4, in the lear it's shift+3), you should see both throttles moving with eachother.
If that doesn't work, try calibrating your joystick.