Ryan, the Code 11 sums it up pretty thoroughly... Actually depending on how completely it's losing power it could lose the stored codes too. The TSRM specifies what you need to test I believe but here's a quick list:

100A Fusible Link, EFI fuse (just replace it), Circuit Opening Relay, EFI relay, clean and tighten the EFI/ECU grounds (connected to the intake manifold toward the rear) and make sure it's mounted securely.

Here's the wiring diagram so you can see how it is all connected:
http://www.cygnusx1.net/Supra/Librar...px?S=Main&P=46



Forgedoil, look in the MKIII FAQ section for details on checking for diagnostic error codes and pot back in a new thread. Posting about your vehicle's problems in someone else's thread while they're still actively trying to fix it usually only causes confusion as your issues are not likely to be related.