Take a step back ...
Seems to me what is needed is a logical, systematic approach to diagnosing this problem. Throwing parts at it will cost you MUCH more in the long run than finding a good independent mechanic. I'm sure Toronto must have a couple dozen of them! I agree that I wouldn't necessarily want to rush off to the dealer with a problem like this, but an independent worth his salt could spend an hour or two very productively and track it down.
If you do want to pursue this further yourself, you might want to repost it with a more appropriate and descriptive subject line. This MAY be more likely to garner some attention from the professional techs. I'd be very interested to see what Donnie or Steve B. would do to figure this one out.