car still diseling run on prob

Im getting tired of all this trying to fix the run on problems. I wish I just keep the 318. I adjust the idle mixture screw and it wont start sometimes, then I adjust it again so It starts fine and idles, but then it idles low at like 500-600.. If i put more it gets to 700 or 800 but then when hot it goes even higher and then I get the run on problem. Im getting so frustrated. And is 1 3/4 turns on the idle mixture scres ok? thats were I get the most vac.