Pcv is rattling

Well now that I have about 200 miles on the engine it has decided to quiet down ..instead of a 2 inch swing it sits on one spot and vibrates .5 or so of vac..very smooth now,,,what gives..it still feels like a vac leak,but there is no miss at any rpm,,,262 cam..i still havnt laid on it but iv nailed it a bit and it pulls relitivly quick[355 gears..]and doesn't fall on its face..i havnt done a speed plug color check yet timing is back at 10 initial and about 38 total..with a slight ping on cracking the gas at cruise..[did the spray around the carb and man] what condition positively tells there is a vac leak?...tx..j