I'm having some similar issues with my 97lx with an explorer swap and pi intake. Just replaced upstream o2s today and new plugs, seems to have helped but not fixed. I couldn't tell you how old the o2s where 304k on Odom so I didn't feel bad replacing them. But I also have a code for vent canister but don't know why. I'm thinking I may a have a vacuum issue in that area I get vacuum coming into that area but it doesn't make it to the charcoal canister so gonna do some digging into that issue when I have the time. Anyone know a good process in testing that function?