i have two blazers the 97 that iam bout to put a new engine in and a 91 that i cant get to pass emissions it has high everything wondering if anyone would know what to check first... the port where the pcv valve hooks to the throtle body was closed with carbon build up. i cleand it i know it needs a new pcv valve just wondering if annyone had any ideas for where else to start

 

sounds like you need to give the top end a good cleaning ....then see if it throws you any codes. then start there.