I ran across this problem yesterday on a piece of equipment at work. Vacuum leak somewhere was causing erratic idle, and hard starting in the morning due to someone adjusting the carb to try and compensate for the vacuum leak.

Unplugged the vacuum line to the brake booster, plugged it, and the idle smoothed out. Replaced the booster, re-adjusted the carb, and it runs great now.

88 4R, 350 V8, R150 5 speed Sold <...uot; />
97 4R, stock, daily driver
98 Sienna, kid and dog hauler, wife's ride