[valiant67]

Are you sure it's starving for gas and not something like the exhaust blocked? Have you pulled the spark plugs and looked at them? Fuel mixture is controlled by the computer. You may want to check fault codes:
http://www.allpar.com/fix/codes/index.html

 

[chuzz]

I'm thinking like Mark. Have you checked your cat con or muffler to see if they're stopped up?

 

[Bob Lincoln]

Are you sure it's starving for gas and not something like the exhaust blocked? Have you pulled the spark plugs and looked at them? Fuel mixture is controlled by the computer. You may want to check fault codes:
http://www.allpar.com/fix/codes/index.html

+1 on this. It's not starving for fuel if it flows as you describe. However, a plugged exhaust or failed catalytic converter would do this. If you unbolt the exhaust from the manifold, or drill a hole before the catcon, I'll bet it behaves correctly.

 

[andr3a]

I'll check the codes and the cat but would I just passed the smog test if my cat was clogged?

 

[ImperialCrown]

If the 'Power Loss' or 'Power Limited' (check engine) light is out, there may be no fault codes. Does this warning light come on at 'key-on' for a bulb check?
Spark plug tip color may tell a story of fuel mixture which would offer an important clue.
If this lack of power doesn't show up for the first couple of miles when cold (open loop), it may be an O2 sensor issue. The O2 sensor doesn't come into play until the engine reaches operating temperature. If the O2 sensor 'thinks' that it is seeing a rich mixture, the PCM will back off the injectors to run very lean and vice-versa.
If the truck is running lean (starving) due to high fuel demand situations, it would be good to verify this. A fuel gauge at the throttle body can monitor fuel pressure while driving in view of the driver. You might have to make up a hose 'tee'. 145177d1247637914-fuel-pressure-gauge-07142258.jpg
Be sure that there are no leaks before starting out on a drive. Pressure should stay around 14-15 PSI (95-105 kPa) and hold steady on hills and under acceleration/load.
If it falls off under load, then we have to find out where the drop is occurring.
There are filter screens at the injectors and both injectors must spray equally without trickles or drips. The fuel pressure regulator (FPR. See #8 in the image) has a rubber diaphragm that can rupture and push raw fuel into the intake manifold through its vacuum hose (see #14 in this image): 0000062J.jpg

 

[thebluesguy54]

I would check vacuum. Also check compression.

 

[andr3a]

Thanks ImperialCrown, some great suggestions. I will definately try all those in the next week or two and get back to this post with the results.