My mechanic found that the oxygen sensor was not functioning. It turned out
to be my S&S headers.  The threaded insert for the oxygen sensor what too
high in the pipe.  Once the insert was cut out and a new one welded in lower
the oxygen sensor started functionally properly.

The S&S header threaded insert is just a nut welded to the top of the pipe.
The treaded insert on other pipes I found is almost flush with the top of
the pipe.

I tried to contact S&S many times but they never reply or call back.

Has anyone else noticed this?

I fail to see how S&S headers is the best option for your van if you want to
maximize
performance.

Jim