My mechanic says the oxygen sensor on my 85 Vanagon is not functioning at
less than 3000 rpm. The HC are very high, and I need to pass an emission
test in Colorado. He thinks that the sensor might be setting to high in the
exhaust pipe, and not getting exposed to the exhaust.  My exhaust pipes and
free flow muffler are made by S&S Headers, and are 2 years old.  The cat is
also 2 years old and made by Emico.

Has any one heard of this?

Thanks

Jim