Your 'Julian date' is really important for ordering parts; don't specify clearly enough, and you're going to do a lot more driving and waiting for parts and returns!
I have a late-year '03, and the throttle body is different than the cars made the day before the change-over... in other words; after July you got a "revised" bracket for the cables and TB. I needed to go to a capable shop with a dyno; they ended up using an oscilloscope function (or yourself on a high-end scan tool)...
You may not need to do that; but the fact that you have to load-up the potentiometer to make it function... I think you may need to check your VIN carefully and reexamine the part numbers. There should be contact with the throttle body pivot pin, but not an excessive amount of twist to line everything up. The gents that dyno tuned the car left the machine screws tight enough to stay put, but loose enough to wiggle... somewhere, while sloooooowy rotating the tps sensor millimeters; the throttle input signal smoothed out and the idle settled nicely after that. What they did isn't something you can do in the driveway unless you got the tools and the chops, though. Easy answer is early/late model year part issue.
When I unplug my battery the
Epic Mountain Cruise... coming soon; if you're Mid-Atlantic get ready!