NuiStyles, about your fuel system problem - I'm pretty sure the Supra ECU outputs a 5v PWM signal on the FPC line, which is pin 22A.
This goes to the Fuel Pump ECU (which I'm also pretty sure is nothing more than a large solid state relay) which controls the 12v to the fuel pump. At idle, the FPC signal is very low, so the Fuel Pump ECU outputs only about 9v to the fuel pump, to minimise fuel circulation.
Under high load and boost conditions, the FPC signal approaches 5v and the Fuel Pump ECU output follows that and goes to 12v.
Note, I have not confirmed with a scope that this is the way the OEM system works, however functionally, I'm nearly certain this is correct.
In looking at the Lexus ECU schematic, it appears it uses the same system, so it should work for the Supra fuel pump ECU. Maybe someone else here (Sideshow?) would have some ideas?
I use a standalone AEM EMS in my Supra and I implemented a similar PWM strategy for my system, but using my own components, plus put in a Kenne Bell voltage booster system for those occasions when I'm at WOT and need more fuel than a single stock pump normally delivers. I basically have three levels of PWM'd voltage going to my single fuel pump 8.5-9.5 volts at idle and low load, 12 volts for low boost, and 16 volts for high boost.