If you go to a squarebore holley you`ll need a adapter plate, if your still using the stock intake which will make matters worse.
Have you checked for vacuum leaks? have you checked the secondary`s to make sure there not partially stuck open? Q-jets are somewhat nortorious for this after they get some age on them. remove the air cleaner, open the top rear butterflies, shine a flashlight in the carbs throat and look at the lower butterflies, they may need lubed or possibly deburred.