Yea! The way things are on these cars the sensors are tied to many unrelated functions, such is the TPS. The one issue that we will never know is what the intent of the engineer was when they wrote the computer test function that gives you the DTC codes. The codes can lead you down the wrong path. Who would of thought that the TPS would effect the transmission even though the engine is running fine! I think one thing I can say about the TPS test is that the test does not check for the TPS linear function (true percentage of throttle opening!). Even the shop manual does not explain the testing function intended!
As you found out the TPS does effect the transmission shifting as does the temperature of the transmission oil, stays in third till the oil is up to temperature, then shifts to 4th and 5th gears.