TPS Performance Problem. DTC P0121

Well, I'm pretty much at my wits end now because I've thrown a TPS performance code several times. DTC P0121: Throttle Position Circuit Range/Performance Problem, and no matter what I replace in order to fix this it just keeps on happening. My vehicle is a 2003 Hyundai Tiburon with a 2.7 liter, 6-speed with only 29,000 miles that is also supercharged (aftermarket parts). As for what the car is doing. That's the crazy part. I can ONLY recreate the problem on the highway, and I must drive at least 30 - 45 minutes straight (normal driving - no boost) before it will start acting up. When the problem occurs, the car will just feel like it loses all acceleration (just like hitting the rev limiter), and then after a couple of seconds pass, the car kicks back to life and runs perfectly again. This will just keep cycling over and over again. And you can see the voltage drop on the TPS (with the mafterburner software) during this whole ordeal. Now, the crazy part about this is that, in order to fix this temporarily, all that I have to do is reset the ECM by pulling the fuses for a few minutes. After I do this, the car will run great and it will take another long drive to get it to act up again.

Here is a list of things I have tried since throwing this code. I have done the following:
1. Ran multiple ground checks on all my wires
2. Replaced the TPS with a brand new Hyundai OEM sensor
3. Redid the splice connection for my TPS on my Mafterburner (fuel tuner)
4. Replaced the ECU with a known good one.
5. Cleaned MAF sensor - didn't do anything for me.
6. Replaced MAF sensor with Hyundai OEM sensor.

The only two sensors that I can think of that would possibly cause this to happen would be either the ECT or IAT sensors, but I'm not even 100% sure of that.

So if you could please try and push me in the right direction, I would greatly appreciate it.

Thanks!