Yeah, unfortunately. It doesn't look good for third party intervention. As stated mostly above, your best bet is to take it to a dealer that wants to have repeat customers and perform the remaining service intervals... much like getting a second opinion.

You might also want to check with the Ontario Ministry of Consumer Services: http://www.sse.gov.on.ca/mcs/en/Pages/Motor_Vehicles_Car_Repairs_Warranty.aspx

It wouldn't hurt to give the ministry a call.

edit: another place to try: http://www.omvic.on.ca/ Which enforces the Motor Vehicle Dealers Act. Their tag line is 'call us if you feel you have been treated unfairly by a dealer'.

Try those two options for some advice on how to proceed. From the sounds of it, you are dealing with a dealer stonewall as opposed to the manufacturer from doing anything. Further, if you the over-rev is true, and that would deny you warranty, then according to the Ministry's pages, that could be considered a 'key item' and you have 90 days to cancel a contract if a 'key item' was not disclosed to you at time of sale. I'm not sure how long ago you bought this, but I don't think it has been 3 months...if you can't get anywhere with the Mitsu dealer, you might be able to return it to the used dealer for a full refund.

cancellation letter: http://www.omvic.on.ca/services/consumers/cancel_agreement.htm If you knew the timing chain was stretched, you wouldn't have bought it...not at that price anyways.