vacuum leak at throttle shaft?

76 Roadrunner, 318 2 bbl. It started and idled great TILL I removed a too light return spring. I added a new OEM spring, and now will NOT idle. I checked at the throttle shaft and I see it has some play. Can not find that light spring to try it back. Would just a small amount of wobble at that shaft cause enough vacumm leak for such problem!??