This car is driving me crazy.

Here is what I have, ls2 out of a 2006* in my 78 trans am with t56. I am running a qft hr-780-vs carb, with holley sniper gas tank with fuel pump in tank. I have a automotive dual stage fuel pump regulator knocking the pressure first done to 12 psi and then down to 6.5 psi for the carb. My ignition is msd 6014 box.* Timing starting at 15 and going to 28 all in by 1500 rpm.*
here is my problem. The car will not run right.**I have the idle circuit good with afr in the 13's. But anything after 1/3 throttle under load the car breaks up, bogs, backfires and sometimes stalls. Seems like it is going lean.* Not sure if it's carb tuning or fuel starvation.*
Thanks for any advice or help!!

Dont know if you still need help but it sounds like you need more timing. I did a little research and it seems they like more timing. Starting high like 15 degrees advancing to 33 or more. make sure you dont have any vacuum leaks as well, at low rpm it wont effect it as much. What are your afrs when it breaks up?

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Originally Posted by NorthFalcon

What are your afrs when it breaks up?

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same question

Just wondering if this was ever resolved and what the exact issue was because im dealing with the same exact issue with my ls swap thirdgen

https://documents.holley.com/199r11667.pdf

Vacuum secondary tuning looked interesting.