Does anyone have a pic of the throttle pedal assembly? I was running the car and the throttle stuck wide open. Is there a return spring on the pedal itself. The carb seemed quite free and it omly stuck when I used the gas pedal, not when I reved it by hand.

just the return spring forward from the carb horizontle throttle pin to the bracket on the dr front of the intake. Take the throttle cable off of the inside edge of this horizontle pin & see if the cable/pedal is free.

It has been a long time, but,when I had my first 70 Duster I discovered there was a raised "bump" in the floorpan just in the area of the "floating" gas pedal travel and when you "punched" the pedal hard enough it would catch the lower edge of the pedal on that "hump" and would jam in "w.o.t." I do not know if the floor pan profile on your 72 is the same as the 70 but it might be worth checking out.
I cured this by cutting about 1/2 inch off the bottom of the pedal.Hope this info helps, good luck.