engine struggles when secondaries open

[puppster]

I've been trying to diagnose a problem with my fathers car. The engine is a 351W with performer heads (2.02 valves) I believe the cam is a XE284H from comp. The carb is a holley 750DP. The car runs great all the way to redline if you don't get into the secondaries, as soon as you do, it really feels weak (sputtering like), and sometimes will clear upand go like crazy.

We have increased the squirter from a .33 to a .37 and this seems to have improved things by introducing more fuel, but it seems now that it will not clear up and run great, so I thought it must not be the pump shot that's defiecient. Next, my father increased the jet size to a 78 from a 74?. He says it feels much better.

My question is are we way out of line with squirter sizes and jet sizes? He was thinking of going to the 80's next. Or does this sound more like a power valve issue? I'm trying to learn, and have no experience with this kind of tuning. I'm sure I should probably get out and run it where I can shut it down to inpect the plugs, but that isn't that easy in the city.