Life of electrical bits? (was: Strange Shuddering)

[John Larson]

IME, and I do lots of tuneup related business, spark plugs on your car 
have a maximum effective service life of around 15K miles.  I have most 
of my customers on a 10K mile service plan, but they "could" go to 15K 
without much problem.  I suggest you take a look at the plugs.  Caps, 
rotors, and wires usually last far longer.  The wires on my 250K 90 20v 
are original, and the cap and rotor have lasted since I replace the 
distributor at around 100K.  John