> If, indeed, the O-ring seals in the cylinders are shot, why is my engine
> performance so good?  Quite frankly, when I have my van out on the
> interstates, it wants to go faster than is prudent even here in Georgia.

It doesn't take much of a leak to pressurize your cooling system over time.
And, it only has to be from one cylinder.  YMMV?

Check the thermostat, cap, and bleed the system.  Do a pressure check.  Head
gaskets are certainly the cause of last resort, but despite what all the
die-hard wasserboxer lovers say, this engine is notorious for this problem.
:-(

Good luck,
Brian