hallmarc

First off, I have an 01 GMC Sierra 2wd 1500, 4.3 vortec (W engine code) automatic 4l60e trans. Ok here's the problem, first thing in the morning this truck is really hard to start, when you hit the key its like it tries to but falls short, I have spent up to 30 mins getting it started (not constantly) when it does finaly start, it diesels for about 2-3 seconds then maintains a normal idle. Once it starts I drive about 10 miles to work and cut it off, 8 hours later starts fine. But it runs kinda sluggish, and the exhaust smell is pretty strong and gets about 12-15 Mpg (normally gets about 22-25)...
What I've done so far: the fuel pump is about 5 months old and seems to be working fine, the distributor is about a year old, the dist. cap, coil, rotor button, wires, and plugs are all new. The cat converters have been gutted out to see if maybe it was that and haven't been replaced yet but everything has been welded back on. The IAC motor has been cleaned and didn't seem to change anything. The EGR valve was somewhat sticking, cleaned it up and put it back on, no change. Scanner shows a P0449 code, but is pretty normal being that I rarely kill the engine while putting gas in it. Fuel pressure is 52 lbs with engine off, 50 lbs at idle. Let it build pressure and just turn the key off and the fuel pressure slowly drops to 30 in about 10-15 minutes. I have been told by someone that it has some sort of pressure relief that slowly let's the fuel back into the tank, but don't know how true that is. I thought the pressure was supposed to hold. When I changed the plugs last night, the truck sat for about an hour before changing them and none of the old plugs, I'm thinking that if it was a leaky injector one of the old plugs would have smelled like gas, but none of them did. Now I'm leaning towards a fuel pressure regulator, but I'm tired of spending money on not getting it fixed...
Any ideas???

2wd-K5

you could chase that code around forever it is an evap code and there are a million things that can cause it, and i dont know how to tell you to throw parts at it lol, stupid things like a gas cap can make it throw the code though. the gas smell in the exhaust is from gutting the cats, and it is a good thought that it may have tripped the code, i would replace them, you truck will never run right without them, lean conditions are a bitch and break valves and the rest, once new cats are in, clear the code and see what happens, you cant pull the cats in a vehicle made after '95 without a custom tune for it, and thats another option too, a custom tune
*edit- unless you live in california or another state that requires a sniffer*