I have a 2000 Pontiac Grand Prix and am getting a P0122 code. The scan tool indicates 0% for the TPS for all throttle positions (engine off and on). Voltmeter checks at the TPS indicated normal operation of the sensor. Where do I go from here with troubleshooting? Also, the transmission shift points have increased significantly. Shift point for 1-2 is 35 mph. Could these problems be related?