[ls1nova71]

If you've driven it 20 miles, there should be no air left in it. Are you running an internal or external fuel pump? It almost sounds like you're losing the fuel prime and the long cranking is giving the pump time to re-pressurize the system. I would put a fuel pressure gauge on it and make sure that the pressure doesn't fall back off instantly. It should hold pressure, if it doesn't you most likley have a leak, if it's an intank pump, it could leak pressure but you'd never see it leak any fuel. I've seen fuel pumps that wouldn't hold pressure too, and the only fix I know of for them is replacement.

You're correct, a 2000 should have a return and the fuel pressure regulator is on the fuel rail, I think what the other poster was refering to was a fuel pressure gauge that screws onto the schrader valve on the rail, which is what you need to get to make sure your pressure is good and steady. You need about 58 PSI, less it will usually run but won't runn as good as it should.

Hope this helps.