In a nutshell:

I'm working with an 86' Pontiac Pariesienne, originally equipped with a carbureted 305. This motor packed it in (jumped timing chain, rear main leak) so rather than repair I went and bought a GM crate motor P/N 12499529. I also bought an eledbrock 3701 performer intake. I've re-used the stock rochester Q-jet carb from the original 305. I transferred all the pulleys, fuel pump, etc installed the new motor went to start it up and it will start then die. If I hold the throttle so the motor starts and revs at 1500rpm or higher it will keep running, as soon as I let off the throttle it will come down past 1500 and shut down. When it's running I can hear what sounds like a belt squeaking sound, but it seems to be coming from the rear passenger side of the engine. (Hard to pinpoint location of sound) I have found tdc re-wired the distributor about 4 times now but each time it dosen't make a change. I've got new plugs, new cap rotor and coil. I've tried another Q-jet carb from a running engine and it has the same problem, making me suspect an issue with the intake. I went to try using the stock 305 intake from the old motor, but I found the exhaust crossover is completley carboned solid and I don't know if it's a good idea to use this intake in the condition. Does anyone have any ideas?