it isn't on behalf of the ECU upgrade though. I would be more than happy to help you determine what the source of your problem is if you would be so kind as to give me the opportunity. As long as you are running 93 octane fuel with the a-class program, you aren't going to have issues. If you need a c-class program, I would be happy to take care of that for you at no charge. If you would please, contact me via email at agpowers@bellsouth.net and I will be happy to get you straightened out.