'Wobbling' freewheels is almost unavoidable and is present on virtually ever single FFW I've ever seen/used. It's not a problem in itself and is caused by the thread on the crank not being 100% concentric with the BB axle which happens during machining. The only reason that would be causing any noise on your bike (provided the freewheel is ok in itself) is if you're chain tension is varying enough to be super tight at the 'tight spot' and so is crunching the sprocket surfaces a bit. You should be able to see this when you spin the rear wheel though.