So I’ve have to make another account, last one wouldn’t let me log in, I’ve got a 1997 p38, little under 58k miles, having all kind of problems, replaced a full list of parts, still stuck, I’ve read online today that the fuel temperature sensor have a fail safe of 40’c mine currently reading 42-46’c, if I slightly clamp off the fuel return line the car runs perfectly, if the temp sensor is in fail safe mode, would that cause it to drop in fuel pressure?
Had it on the emissions tester today and the lambda reading was through the roof, co and hc were in spec, when you let off the throttle it initially came back within spec then instantly fall out again

On a GEMS the fuel pressure regulator is purely mechanical (diaphragm and spring) so not going to be affected by the temperature sensor. What does the fuel pressure read when running and what does it read with the return clamped?