97 Jimmy PCV Problem

Hello I have a 1997 GMC Jimmy 4WD. I was in Autozone the other day bored and I decided to change the fuel filter and PCV valve. I bought them and brought them home and changed them. I noticed better gas mileage. But I also noticed a wierd noise. There is a hissing noise where the PCV valve is now. Before I changed the valve out there was just a slow rattling noise. So I tapped on the hose and the vavle rattles now but very fast. It sounds way different than before. I dont know what to do. Why would it sound different now after I changed it. Also when I first start the truck the Valve just hisses and then I tap on the hose and it rattles/buzzes. It seems like there is too much vacuum or something. Any suggestions on how to fix this?

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