I have throttles set to idle, yet on taxi, my 737 continues to move slowly but picking up speed forcing me to ride the brakes. Is this normal operation or is my throttle calibration off?  

Your throttle calibration is off. Nothing wrong with the NGX. At Idle it doesnt move or just barely depending on your weight. In real life it should move on its own with idle thrust, but there is that friction bug that plagues us all regardless of aircraft, unless the dev made some compensation which I believe PMDG made some in the .AIR file.

 

Try another aircraft and see how your throttles respond perhaps?

I tried Captain Sim's 767 and a few GA aircraft. No problems there. It seems to be happening only with PMDG's 737. 

I tried Captain Sim's 767 and a few GA aircraft. No problems there. It seems to be happening only with PMDG's 737. 

 

Any settings through FSUIPC?

 

Full names in the forum, please - first and last.

Actually, in transport category jets, you would expect the aircraft to accelerate at idle depending on weight and the slope of the taxiway. Most airlines consider 20 kts a safe taxi speed. On a long, straight taxiway 30 kts would be considered a maximum. The technique is to let the aircraft accelerate to a ground speed of not more than your acceptable chosen taxi speed, with no braking, and then apply firm braking to bring the speed back down then off the brakes and let it start accelerating again. This way there is less heat buildup in the brakes than there would be if you constantly ride them. Hot brakes diminish the performance that you have based your takeoff on.

Of course on ramp areas and during maneuvering and turns slower speeds and more braking will be required.

Cheers.