2004 seems to loose fuel pressure periodically while driving down the road

Define loosing power ? Battery dies overnight ,driving down the road ?

Fuel pump.

Sounds like a weal fuel pump.Check your fuel pressure it should be 48-55 psi with key on and engine off.If its not not within these specs replace fuel pump.

a loose connection

Time to have the timing/tuning checked up. The fault is relative to a cold engine and can be due to poor fuel flow/delivery or poor electrics.
So the check up for replacement of suspected components like plug, filter, coil , HT wires fuel pressure must be made.

A fuel pressure test should be performed as I suspect the fuel pressure regulator is leaking fuel into the vacuum line causing the engine to flood on restart.
A drop in fuel pressure would confirm this.

3.1 AND 3.8 ARE KNOWN FOR UPPER AND LOWER INTAKE GASKETS

fuel goes bad after a while and can bleed out of the lines after sitting that long drive it like it's stolen, add some fuel treatment and give her a fresh tank of fuel and see what you get

Sounds a lot like a fuel rail pressure issue. Re-check your work. Make sure your supply AND return fuel lines are not pinched or kinked.(that won't cost anything) Put a $15 NAPA Gold fuel filter on. At eight years you can't go wrong-it should need it anyway. Next step up in price is to have a mechanic attach a pressure gauge to the Schrader valve and monitor rail pressure as you drive and reproduce the stumbling. I'm betting your mixture is getting FUBARed causing your PCM (computer) to pull timing, that in combination with the low octane gas is causing your mixture to ignite so late it's still burning in your exhaust system. Retarded ignition timing will cause MASSIVE losses in power and dangerous under-hood temperatures. The reason I say dangerous is the GTP engine fire recall situation. http://www.gminsidenews.com/forums/f33/upcoming-recall-07035-97-03-gp-regal-3800-s-c-vin-1-a-61961/
If you’re throwing half burned gas down the manifolds and into the catalytic converter, it will overheat (and glow red or orange) and the internal lattice will melt and collapse (may have already happened) this will restrict the exhaust badly and cause a further reduction in power and more knock timing ******.
LMK what you find after the filter or fuel pressure test. That will tell you where to go from there.

Ya know First i never drive a car at 4ooo RPMS cant remember when but anyway.
Check the Intake Air tube the goes into the air cleaner and throttle body for cracks and cuts and being loose. Fuel Pressure have it checked while you are driving to make sure your noy loosing fuel pressure at the high Rs. Ignition System Factory Plugs and wires no fancy discount suppose to increase horsepower stuff