Need Some Help

[samk]

i have a 90 mustang lx with a 306 (302 .30 over) windsor sr heads milled .30, comp cam with a .613 lift, forged pistons and rods, it was fuel injected but was missing alot, so i swapped for carb, now im having problems, i went a weiand extreme intake and i had a holley 750 vacum sec. carb, when i hit the brakes it diesi have the vacum running off intake, any suggestions, i dont have any vacum running to or from carb no return line and i smell alot of gas