Attention to detail.  Thoroughness.  Persistence.  These are
qualities rarely found in dealership mechanics.  If you find a
mechanic with those qualities, pay him willingly and cheerfully.  As
can be read from many of our posts, we get better service
(sometimes) by checking things out ourselves.  Be a geek.  Buy books
and read.  Talk geek talk with other gearheads.  Gawd I love this
list.

Here's a tip for finding some of those irrascable air leaks in the 
intake system, unfortunately, this requires an aircompressor with a 
regulated output:

-pull off the air flow meter at the rubber boot (just loosen the hose 
clamp)
-replace airflow meter with a rubber ball to seal the large opening; 
if I remember, tennis or raquetballs work
-place nozzle of air gun in just about any vacuum line hose, I use a 
piece of small diameter copper tubing on the end of my airgun for 
blowing debris and sticking in orfices (shut-up Steve)
-regulate air pressure to a few psi or a little higher, one doesn't 
need much
-mix up a soap-water solution and use a soft paintbrush to slather 
all over the intake system; air leaks will foam like crazy!  listen 
for leaks too.
-you may have to rotate the crankshaft soemwhat to get the right 
position to seal the combustion chambers

I've found that the fabric connectors on the maniforld really leak at 
the crimp type hose clamps.  Replace them with screw type.  Also, 
breather tubes seem to leak right at the big boot.