Yes I have also dealt with so many convertor issues and they can seem like its not but can be. I would not overlook very easy to check it and eliminate this from the list. Your fuel is good but the other things that really come to mind is the convertor MAF and timing.
I hope you found my answer helpful, please click on the GREEN ACCEPT button above for my answer. This is necessary for me to be paid for my work and so that I can get credit for assisting you. Your question will not close, and you will still have the opportunity to follow-up if needed. Leaving a bonus and positive feedback is not required, but doing so is certainly appreciated!
If you have additional questions, please keep in mind that I do not know what you already know or don't know, or with what you need help, unless you tell me. Please consider that I am answering the question or question that is posted in your posting based upon my reading of your post and sometimes misunderstandings can occur. If I did not answer the question you thought you were asking, please respond with the specific question you wanted answered.
Also remember, sometimes the news is not what we want it to be and can be expensive and disapponting, but that is not the fault of the person answering the question, so please be courteous.
There can also be a delay between my answers because I may be helping other customers or taking a break.
You can always request me through my profile at http://www.justanswer.com/car/expert-automotivedoctor/ beginning your question with “Snapontech"