[sparky68]

This is from personal experience with similar problems. Beside the other advice posted here:
1. Make sure your valve train is in good shape & properly adjusted. You'll never pass if you have exhaust valves not seating right.

2. Change your oil, filter & PCV, even if you did it last week.

3. I was very disappointed with the other "emissions" additives. But Z-Max really works on several levels. Cleans out carbon deposits like crazy. So make sure your gaskets/seals are in good shape or after its done cleaning you'll have oil leaking from everywhere. I used both the oil and fuel additive and the car passed with numbers in the 25% of allowable range.

Bare in mind, I'm not saying my list is all inclusive. I did most of the other stuff these guys advized too!!!