What is a "Power Balance Test" ? How is it performed ? What does it tell
you ?

I recently took my aircooled Vanagon into a new shop to get my air flow
sensor adjusted. The process of adjustment involved gas analysis and they
found something they didn't like ... high Hydrocarbons (pre-cat
converter), so they performed a "power balance test". I missed the gist of
what the tech was explaining, but did catch something about the "lack" of 
power. 

Power Balance results were:

#1 cylinder: 73
 2         : 62
 3         : 16
 4         :  5

I do know that the head seals on the #1 & 2 cylinders are leaking, which
the tech mentioned. But he also mentioned that there was a "big" problem
with the #3 & 4 side of the engine.

Any clues ?

Thanks, Chris