Jason,

You over tightened the plugs, that is why they cracked. You ARE using a torque wrench to install? I am speaking from experience..been there and cracked that.

Maybe the cracked plugs are causing a ground problem or are shorting/arching?

Sometimes it is hard to keep the 16V faith. If I could sell mine and get a decent price.....I`d buy a Lexus.

Tinker