I know this was a very old post but thought I'd give you an update.
Those who said the grounds were bad were correct. The engine grounds were bad and needed fixing. Don't know exactly how many or to what extent, but it was around $300 worth at my local Ford dealership. Thank God for my extended warranty.
Oh, and by the way, that car is mine since my oldest is now driving a 2003 SVT ZX3. And, unfortunately, he's starting to experience the same symptoms.
Anyway, thanks again for all the suggestions.