Sorry to resurrect this from the dead, but I figured I'd share another data point.

I'm using a CH yoke, and just recently bought the C-130s for FSX.  

I also suffered from excessive idle power on the ground...to the point where the parking brakes wouldn't hold the aircraft in place. It seemed to be killing my landings as well - even when I came in at an appropriate approach speed, when I leveled off in the flare and cut power I would usually climb...it was horrible.

Based on what I read in this thread I recalibrated my yoke using the Windows Control Panel "calibrate game controller" routine, and it "seems" to have solved my problem.  The parking brake is holding and I just made a very sweet touchdown from a test flight.

So, step one to solving this should be recalibration of your controller and go from there...

Matt