It has been a close to 10 years since I lived in that area (I grew up in Mission Viejo), but if you go to the El Toro Automotive center, there is a shop on Cherry Street right next to the Big-O tire store that is known for being a good place to have ECM problems diagnosed and fixed. I cannot remember the name of the shop though. From what I have heard, from friends of mine that still live in Mission Viejo, the name El Toro no longer exist, and that area is now known as part of Lake Forrest, so I am not sure what that automotive center might be called now.