> I'm looking for some assistance in finding what ails my beloved vanagon
>7-passenger. I've just had the engine re-built this summer past.My van has
>less power than when it had cracks in the heads. By re-built I mean, new
>heads, not rebuilt ones, and new pistons and cylinders. My air box was
>adjusted, as well as my timing. But my problem still persists.The van gets
>to operating temperature, then gradually loses power.

Of course, there are many possible causes of your problem, but here is one  
possibility...
Since your problem occurs as the engine warms up, have you checked the head 
temp sensor?  This is supposed to adjust mixture based on engine temp. If 
it were delivering the wrong resistance to the ECU as it warmed up, this 
could cause an idle mixture problem that might not have been noticed if it 
was adjusted while the engine was still somewhat cold (before the temp 
sensor heated up).  I think the Bentley manual will tell you what 
resistance the temp sensor should show when warm, so you can test it with 
an ohmmeter. Or you can temporarily ground it out (which will make it think 
your engine is cold, thus run rich) and see if this has an impact on the 
symptom.

-Ron Salmon
 The Bus Depot 
 http://www.busdepot.com