new carb hesitating a bit

[v8s10kid]

i just put a new holley 570 cfm street avenger on my s10. it seams to hesitate till about 2700 2800 rpms then takes off. are the secondarys opening too late?

a little info:
1984 chevy s10
305 small block
edelbrock performer intake
shorty headers
2.5 inch custom exhaust with flowmaster mufflers
pertronics electronic egnition conversion
muncie m20
3.08 rear
weights about 3240 with me in it (thank you scrap yard)

altho my old edelbrock carb ran a little rough, it never hesitated like this. also, i didnt change anything else. timing is still the same, and i havnt put new plugs in yet. the vacume advance line should go to the port on the side of the metering block right? or to the port at the base plate?