1982 mustang lx timing problems?

hi all im new to afm as a member but i have used it as referance to solve problems in the past. so here is what im running into maybe someone out there has an idea how to fix it. so i have a 302 with bbk long tube headers , edelbrock f4b intake and an edelbrock 600cfm carb (1406). i just put the carb and intake on and it runs just fine till 3500rpms then feels like its missing? it just loses all power and barley accelerates. i have my timing set at 14 deg btdc what am i doing wrong? o btw idk if it matters or not but i dont have a 5.o h.o firing order. thanks for the help