when you say unplug the fuel ecu do you mean the black plug on the side of the metering unit???
Baiscally with this unplugged the pressure regulator returns to default values, SO NO BOOST, it ignores values given by the air and coolant temperature sensors, so i would start by replacing these and cleaning all electrical connections including earths then let us know if it has helped.
Rob,
PS
check the heated seat fuse mate in the fuse box.
wtf????