fuel pressure issue?
 

i am working on a 94 c1500 with a 350 stroker in it..i have replaced the IAC, Egr valve and fuel pump so far, the problem I am having is when I drive the truck pressing down on the accelerator it works just fine under light pressure, if I try to accelerate quickly there is a complete loss of power like there is no fuel getting to the engine then it picks up quickly when I take my foot off the gas, also coming to a stop after driving the engine stalls. I am not sure if it need a high volume fuel pump to keep up with the fuel demand. I have not had this issue at any other time except when the truck is in gear, in park it runs just fine even revving it up and releasing the throttle quickly. The ECM is not showing any codes at all every time I have put a scanner on it, not sure of what else to look at...anyone have an idea?