tunnel ram

Awesome weather today. Started my car today after adjusting the carbs some. I have the front blades to where the t-slot is square. The back blades or 3/4 turn open. Ive been chasing the idle. I can get it set and its good for a couple minutes. then it leans out. So I turn the idle mixture screws out and idle comes back. After a couple minutes it goes pig rich. So I turn them back again and same thing. Back and forth like this. And either way its pig rich of idle. It will clear out at 2500 rpm in 10 seconds or so. I tried to open the back more and close the front and readjust but cant fined the right spot. No power valves. Its not pulling though the boosters of idle so I don't think that's the problem. If I whack it its very crisp. If I go at it slow it sounds like crap and loads up for a while. Suggestions please. Thanks. I'm starting to think vacuum leak.