I have tested the pressure 55psi I broke down and went and picked one up.

 

the vortec motor is the "w" code motor (cpi) ("z" code - non vortec). the vortec motors have what i like to call the "fuel injector spider" on the underside of the upper intake. the spider is only made of plastic, which dryrots. 99% sure thats the problem if you have the vortec cpi motor that looks like this - http://www.tweaknews.net/decarbon/cold.JPG. hers a pic of the spiser in the intake manifold - http://robstark.com/graphics/parts/cpi2.jpg. and heres NAPA's pic of the itemby itself - http://www.napaonline.com/MasterPage...Injector+-+New. hope this helped!

 

55 psi is too low to start. You need 60-64 psi for that engine.

You need to look under your intake plenum and see if you have any leaks - it's possible the fuel pressure regulator is leaking, causing the lower pressure. Fortunately, that's a $45 part (plus the ~$15 intake gasket).

If you pull the plastic Vortec cover (T-30) off the top of your motor, you will see a round thing in the center of the plenum. That's your IMTV. There are 2 more Torx screws holding that down - I think they're T-20. Unplug the connector, then unscrew them and gently twist the IMTV side to side. You might need to spray some WD-40 around the edge to help it break loose. Be gentle; there's an O-ring sealing it to the upper plenum and you need it intact. Once it's free, pull it out. Look inside with a flashlight: if you see any clean spots (will look gold-colored) on the passenger side, your fuel pressure regulator is leaking. If you have clean spots on the driver's side, it might be the 'nut kit' leaking (about $60, I think). If you see any washed areas, it's time to pull the plenum. Note on reinstalling the IMTV: lightly lubricate the O-ring with a little engine oil.

For that, you'll need a 10mm deep socket. There are something like 10-11 nuts/studs around the outside of the plenum to remove. Make note of which goes where - they're not all the same. Take pictures; they can be really helpful.