I have a 99 Dodge Durango with a 5.2 i have replaced the alternator fuel pump and the heater core as well as water pump thermostat wheel bearings rotors Brakes shoes new tune up wires and plugs about to replace distributor head and injectors but my question is what causes delay in the start of a engine that is warm i can cold start just fine but once i park come back get in and it's still warm i got to pump the gas pedal to get it to start and ive already replaced the fuel pump.

 

Might try cleaning the throttle body, and then resetting the system. (just leave the battery disconnected while you are cleaning.) Another possibility would be a cheap fuel pump.... What brand did you put in?