350 not getting enough fuel

[OrangeC20]

So I bought a engine out of a 89, throttle body, and I put my heads and intake, off of a 74, carberated on it. I had to put in a electric inline fuel pump. It runs awesome up until my secondaries open up then it falls on its face. If I keep it wide open it will start lurching. Thanks for advice on advance.

 

[1987 GMC Jimmy]

Just to verify, your intake manifold is mounted to that TBI motor correctly? No vacuum leaks? New carb or previously used?

 

[HotRodPC]

Where did you install the inline electric pump? And what's it's pressure rating? Inline electric pumps really like to be closer to the tank. They can push the fuel better than they pull the fuel for long runs. Hopefully you're getting at least 5lbs of pressure at the fuel inlet of the carb.