This post is nine years old, but thank you for the addition. The biggest misconception that you eluded to is the fault codes did not say to replace the TPS or that it was bad. Fault codes never say to replace a part. They only indicate the circuit or system that needs further diagnosis, or the unacceptable operating condition.
Water gets in the engine compartment any time it's raining, and water will not hurt a throttle position sensor. The other misconception was that the fault codes couldn't be read because the Check Engine light wasn't on. On '96 and newer vehicles there can be over 2,000 potential fault codes. About half of them refer to things that could adversely affect emissions. Those are the codes that turn on the Check Engine light. If any of the other 1,000 or so codes are set, the light never turns on, but they can still be read. '95 and older cars only have a few dozen potential fault codes, but still the Check Engine light only turns on for those codes related to things that could affect emissions.
The biggest clue that was glossed over was wiggling the connector had an affect on the symptoms. The way to approach this is to view the TPS signal voltage on a scanner while moving the connector. It is fed with 5.0 volts. Due to mechanical stops inside it, the range of signal voltage goes from 0.5 volts at idle, (approximately), to 4.5 volts at wide-open-throttle. If the signal voltage is wrong, but stays within that range, no fault code will be set. A broken ground wire will send the signal voltage to 5.0 volts. A broken 5.0 volt feed wire will send the signal voltage to 0.0 volts. Either of those conditions will trigger a fault code for "TPS voltage high" or "TPS voltage low". It is possible, but very rare, to have one of those breaks occur inside the sensor itself. The chance of that happening to a second or third sensor is very unlikely.
My suggestion was going to be to replace the plug, but that was done already. That leaves just one last suspect. The 5.0 volt feed wire and the ground wire for the TPS are shared with a number of other sensors. Only the signal wires are specific to each sensor. That means those two wires each have a splice in the wiring harness. Those are just ripe for corrosion and intermittent problems. My suspicion is it wasn't changing parts that made the engine run better for weeks or months. It was flexing the harness while doing the repairs that caused the change in symptoms.
Wednesday, August 9th, 2017 AT 4:55 AM