Have a question for you all. I bought a non-running 1990 XJ. Found computer was wrong in it, and this has been replaced with a new one. Now, it will only start with "ether", then runs so-so. I need some info on how to determine which sensor is causing this problem. Is there a code scanner I can get fairly cheap to diagnose my computer nightmare? Do not want to start replacing sensors by the process of elimination to find the faulty one. Please help!