Need help F-250

I had just bought a 2003 F-250 super duty V-10 had been sitting for just about 2 years not running.
When i got it home i had found that the fuel pump was out and i replaced it and it fired up.The truck runs smooth and very strong.It has been about two weeks and now if i put it in gear within 10 seconds it dies it dont matter if i give it gas or not it just dies. It does still have the fuel in it from when it was sitting I plan to drain that fuel and replace the fuel filter.
My Question is does anyone out there no if this could cause the truck to stop like that or should i be looking at something different. My plan is take to a mech at some point but with the purchase price and the registration back fees im tapped out.
Thanks for any feed back you might have