Grand Junction, CO:
It appears that records relating to the mechanical work, communications between you and the previous owner, and the process you used to take possession of the car would go a long way to proving you did not steal the car or forge a title. I am sure you have shown this evidence to your current attorney. I cannot think of a reason why your attorney would think it is not good enough. You need to ask and get a clear explanation your attorney.
If you have documentation that the the vehicle was used as payment, an attorney should be able help you. Make sure that you are showing the evidence to an attorney who represents you. The district attorney or prosecutor, does not represent you. Rather they represent the state and their goal is primarily to secure convictions. Even if you show them evidence, they may be unwilling to dismiss a case and you need an attorney to fight for you. If you do have your own attorney, either a public defender or private attorney, ask them specifically what their concerns about the case are. Sometimes there are things that cause attorneys to be concerned that clients may not understand. For example, in court, certain rules restrict the kinds of evidence that can be used. A good attorney will explain everything to you. Consider getting a second opinion if your lawyer will not explain the problem with your case.
Please remember that legal matters are complex, and that even the smallest details can have a great impact on a case. It is always best to meet with an attorney in person to discuss the full details of your case. Furthermore, remember that I am not your attorney until you have been to my office and we have both signed an agreement. If you would like to discuss having me represent you, please call or email me, or visit my website at http://jenkinslawco.com.
You need to hire a Public Defender or hire a private criminal defense attorney as soon as possible.
The information provided in this answer does not create an attorney-client relationship. If you are interested in his legal services, feel free to call Chris at (303) 409-7635 at his law office in the Denver Tech Center. All initial consultations are free of charge.