TPS
Dre, I purchased the scanner at Autozone for about $35 and it is invaluable. When I replace parts on any of my cars, I always check to see if a parts store carries the part that I suspect is causing the problem. If the parts store says, "that's a dealer part only", I continue troubleshooting the problem. Although any part on a car can break, parts stores generally only carry parts with a high failure rate. An example is most any parts store can sell you an O2 sensor or fan belt, but ask for an EGR valve and they might be able to order it or might recommend going to Ford. My point is that auto parts stores are very reluctant to carry parts in their inventory that might sell. When I asked the Autozone sales clerk how many Throttle Positions sensors they sell, he said about 6 per month for my year model and he had 3 in stock. Evidently the TPS is a rheostat that changes the voltage going to the computer. The computer uses the MAF to determine the actual flow of air and the position of the throttle to adjust the mixture of the gas. If the voltage reading from the TPS is out of range, the check engine light may illuminate briefly. You would then need the code tester to verify. My Explorer has 128,000 miles and I started having a slight ping at around 90. I believe the TPS was starting to give inaccurate voltage readings when the throttle was open more than the normal cruse settings. The rheostat starts to wear out in the area were the throttle is normally set after about 70,000 miles. My TPS created a lean condition were I should have had a rich mixture.
Sorry to ramble on. The TPS is $39 at Ford and $26 at Autozone. I'm sure Pep Boys carries it also.
Good luck.
