One thing to check is to make sure the metering rods are all the way down at idle, it they are bouncing or not fully depressed, it will throw off your A/F. It's easy to check, just loosen the caps and rotate them enough to see the rod- do one on each carb, all 4 to be through. Then start it up and see. If the springs are too stiff for the idle vacuum of your engine, you will need to replace them. If all 4 are good, then just move on from there. I'd suggest fresh plugs-or sandblast cleaning and re-gapping the old ones and giving it the old Italian tuneup and see how it goes. Remember timing needs to be set right first, then idle speed, then mixtures. If you've got vacuum leaks or the throttle shafts are worn or binding, it all needs to be fixed first. I'm not trying to talk down to you, so if it seems too basic, it's not an insult. I just don't know your background or anything about the car you are working on. If you've got an aggressive cam in it shoot for 1000/1200 rpm at idle, as long as it isn't dripping fuel from the venturis and the mixture screws are able to affect the engine speed. You've got the basic balance taken care of so after blowing the carbon out get the idle mixture set and go from there. It may be worth your time and money to get it on a chassis dyno to get it tuned. HTH, Steve