[jhv48]

Throw away the vacuum gauge and adjust the four idle screws so that you get the highest idle. Once you have determined this point, drive the car. If it still bucks on light throttle tip in and/or decelleration, open the idle screws another quarter turn and test drive (opening them is making the mixture richer). Keep doing this until it smooths out.

Unless your choke is slow to open, or remaining partly closed, idle screws that are only open 1/2 turn are quite lean (perhaps compensating for high altitude or sticking choke).