i have a holley 5200 off a pinto on my 87 b2600. as a side note i have had a weber on there also and it did the same thing to me. the truck will start fine, idle fine, as soon as you start to give it any gas it will rev up and when you get to about 2000 rpm it will start to spit gas out of the primary shaft and start to bog down and then when the secondary starts to open it bogs way down and dies. i thought maybe it was to much fuel from factory pump so i regulate it down to 2.5 and that is not enough gas. i am stumped. please help.

 

The holley 5200 only needs like 1.5 - 2 psi of pressure. Perhaps you have an engine problem if this is the second carb with the same issue?