BAMF Z71

I bought a '99 Silverado Z71 w/ 4.8L about a month and a half ago. When I bought it, the dealership (a ford outlet lot) had just received it in on a trade and had only taken it for a short drive and barely had time to look over it. I bought it after they said they were going to replace the fuel pump in it as it acted like it was starving for fuel for the first, oh lets say 30 seconds or so, until it got warmed up. It worked fine for about a week and then it started acting up doing the same thing. I ran a "fuel system cleaner" through it and that worked for about 3 days. I crawled underneath the other day and looked and to me it looked like they didn't even replace the fuel filter. I've been busy with work and school and finally got a day off tonight and said to hell with procrastinating. So I put on a Wix fuel filter, changed the oil, started it up and it's doing the same damned thing. My father works at John Deere and is bringing home a fuel pressure tester tomorrow night but I'm going to be gone until late saturday evening to a firefighting class.

What other possibilities would there be other than the dealership didn't replace the pump? Also what would be the next step if the fuel pressure is fine? Anyone ever have similar problems?

Any help is very much appreciated. Thanks in advance.

BTW: My cardomain link for the truck is http://www.cardomain.com/ride/2440325 for those who want to see pictures.