68 440 idles very low after sitting for a couple of minutes

My 68 440 idles so low that it will die if I don't give it gas after it has sat up for a few minutes after running for a while...Example drive to store and then when I come out of store it will start but then will want to die. After a minute or two it is fine again. I have an edelbrock carb with no choke. Any ideas what may be causing the problem?

count the # of turns to get the (2) idle mix screws in to lightly seated then remove them & shoot a 3 second blast of starting fluid or brake kleen (whichever can has a thin red straw for the nozzle) into each screw opening then replace the screws to their orig position. that'd be a start. other than that I would check fasteners/hoses for vac leaks & might need to richen the idle mix screws slightly. EDIT what is the hot idle speed? might need bumping up slightly

I will try the cleaner in the carb. I am not sure exactly what the idle is...the tach is not working. I bumped the idle up some today but when it gets hot it idles faster than I think it should.

Replaced the fuel filter lately???