[shorod]

The dealer told you the pressurizes, but then bleeds off. Is this with the key turned to the "Run" position, or with the vehicle running? If this is just with the key to run, this is not indicative of a faulty fuel pump, but rather a faulty fuel pressure regulator or leak somewhere (fuel injector stuck open, etc). If the fuel pressure never reaches specification, then the first step would be to replace the fuel filter before condemning the fuel pump.

You may want to try removing the Sensor 1 oxygen sensor (pre-catalyst) from each cylinder bank and see if that improves the way the engine starts and runs. If that does, then it would seem you have an exhaust restriction.

Also, check the engine timing. If your timing is off, that could cause just about all the symptoms you describe, except the fuel pressure issue.

-Rod