I'm stuck, I've rebuilt the carb, got the calibration kit tried different combinations of rods jets springs and nothing with fix this problem. It's a 600cfm on a 440 with edelbrock intake. Is it too small of a carb for the engine? Bad fuel pump? What else could cause this? It idles perfect, but when I take it on the road it seems like it doesn't have the power it should, the plugs are clear white after a drive but tan after sitting at idle

 

Carbs too small

 

carb is too small for a 440, also I suspect it was jetted for a GM application when new