Mystery problem

[1987GMCSierra]

I had been dealing with issues on my 1987 GMC for awhile, and gave in and dropped a new Jasper 305 in. After installing the new engine, I have been experiencing a new issue where the truck will die after I turn the ignition over. It only seems to happen when it's hot out (which is 24/7 - I live in SC) or when its been driven a lot that day. As soon as I turn it over it will die unless I give it a little gas. When I throw it in neutral, reverse or drive it will die as well - until I get going. I have taken to multiple repair shops and they're all stumped. Here's a list of what has been recently replaced/checked.

-New Jasper 305 Engine
-New EGR Valve
-New MAP Sensor
-New engine coolant sensor
-New Fuel Pump, fuel lines
-No codes being produced
-Fuel injection running clean

I have a bottle of your favorite liquor if you could help me solve this issue. I'm at my wits end!

[bd]

• Have you verified base ignition timing with the brown/black ESC bypass wire disconnected?  What is it?
  
  
• Have you measured the fuel pressure?  What is it?
  
  
• Remove and plug the vacuum hose connected to the EGR valve.  Is there any improvement?
  
  
• When started cold, does it initially throttle up on its own? 
  
  
• Do you have a test light?
  

[Irish_Alley]

does it just die or does it misfire/run like crap then die