I bought a used Concorde LXI. Body looks good. 152.000 miles. Clean car. Transmission was rebuilt by my dealers vendor because it was bad. Now my speedometer doesn't work, engine light came on, and the car runs for a while and than stops. I can start it up and go no problem but don't know what this means. It keeps happening. I bought the car knowing that I would need to replace the muffler. It turns out that I have to fix the converter pipes and Speedy Muffler told me that it would take the Chrslyer dealers to fix that. My questions are. Is my transmission going bad ( I bought as is but hope my dealer has a warranty) and is the muffler related to that problem and do I really need a chrylser dealership to fix my muffler? I've had a long string of bad luck with cars, so I am prepared for the worse. Any help or advice would be greatly appreciated.