Recurrent air leak at base of carburetor

LA 360 (non-Magnum) with Edelbrock Performer intake and ThermoQuad. I'll tighten down the carb bolts but they seem to loosen up again, causing a random miss at idle and low RPM. This has happened twice now. Maybe it is some problem with the base gasket shrinking? Should I should use some Copper Coat gasket spray? Any suggestions appreciated.
Sounds like your low-speed circuit is running on the edge of lean then, and any tiny leak makes your engine unhappy.. Ima thinking your T-port sync is out. Try backing off the timing 2 degrees, then crank up the speed screw to get the rpm back up, and then reset the mixture screws, to the rich side. Repeat as often as necessary or until the idle timing falls below about 10 degrees.