i know this sounds crazy spend the 2 dollars on a pcv valve and make sure u get the orings properly put back in i had this same issue and even had the trans diconnected and belt taken off and car started and still made the noise took a dealership to tell me a 35 dollar diognostic was a 35 cent oring fix.......no promise that its your issue but its worth a try especially with a salvage yard higher mileage engine its a cheap attempt