Thanks for the suggestions for my poor gas mileage problem.  ( I was getting 
10 mpg after I replaced the head gasket).  I was a bit overwhelmed as I am not 
a very good mechanic. I broke down and took the van to the dealer (my mechanic 
has NO computers) as I wanted a complete diagnostic and my O2 set.  They went 
ballistic when they saw all the after-market parts on the engine, as expected. 
 (We can't warranty any of our work, blah blah bla).  I had some vacuum leaks, 
which I did not detect, and the intake manifold gaskets were backwards.  They 
also got rid of that scary valve tapping noise I introduced with the new head 
and gasket.  Besides them wanting to replace everything non-VW on the van (or 
trade it in, guess where I could get a new one..) they said my fuel injectors 
were beyond cleaning ( I have 100K  on them) and I need a new ox sensor.  My 
question is, since I was getting 24 mpg before I messed with the motor, how 
could the injectors be bad?  Will they go all of a sudden or will they die 
slowly.  Also, can I get a used set as I know how much these things cost.

I would like to add that the dealer did do a good job of diagnosing everything 
and had the van back to me in a few hours. (Devon Hill Volkswagen in Devon 
PA).

Thanks,
Bryan