I use Powerstop components on all my vehicles including my '05 T4R Limited. I would not just change out all the components but instead take the wheel off the one that was hot and see if that caliper is moving freely. If not, I would disassemble, clean and regrease if it is not damaged. When you compress the caliper, it is always good practice to open the bleeder first so that fluid is not forced from the caliper back into the system. Recommend use of Permatex Silicone Ceramic Extreme Brake Part Lubricant #80653 which is good for not only the metal parts but safe for rubber and plastic.
It could very well be the interior of the flexible hose running to the caliper is damaged trapping fluid and not allowing it to flow back to release the caliper. This can happen if folks clamp off these lines when removing calipers to keep brake fluid from dripping. Open the bleeder before you check the caliper to make sure that there is no residual pressure holding it. You might want to replace the hose on that wheel, particularly if the caliper is moving freely or if you had any residual pressure- about $68 list/$50 on line discount (Toyota part number: RH Rear - 90947-02D31, LH Rear - 90947-02D32).
Brake fluid should be flushed every two years or so - it picks up moisture over time and can cause internal corrosion. You need to bleed all the fluid out of he entire system, one wheel at a time until you have good, clean fluid. If you are going to be doing brake work, get yourself a Motive Power Bleeder or a Mityvac MV6830 if you have a compressor.
https://www.youtube.com/watch?v=uJ4gRAmNVnM