Ok so I've been sprucing up this brat I bought and threw a brand new weber on it and can't pinpoint my issue, when I start the car I set the electric choke turn the key runs perfect idling at about 1200 to 1300 rpms kick off the choke runs great and purrs at 800 rpm. So the problem comes into effect when it hits operation temp the idle kicks down and sounds like it's running on three cylinders, almost like it has a loppy cam or something. It picks up fine when you give it gas usually,sometimes a hair of hesitation. So things I've changed thus far, new plugs, wires, distributor, alternator, fuel filters, oil filter, fuel reg all were oem stuff. Weber was tuned best lean idle and no vac leaks I could find, any suggestions on things to check into?