On the surface something doesn't seem right, but if the servo is moving at least we know its sorta functional. Before buying new parts, have you started the engine and observed what the RC valve does? It should move as you Rev the throttle. Have you measured the resistance of the TPS? You should be able to see the resistance as noted below.

Red to green should be 5k or so all the time.
Red to Blue should change as you open throttle. Range changes from I think close to zero to about 5k ohms. It should change resistance smoothly. An analog ohm meter works best here.
Green to Blue should change as you open throttle, but the change will be inverse of red to blue.

If the TPS is not giving correct resistance then pgm will not be able to correctly position rc valve.

You could also do some bench testing on the servo motor with a 12v battery. Do you have a copy of the schematic? It shows which pins voltage is applied to.