I have a 1999 XJ sport that throwing a P0123 code. I have replaced the throttle postion sensor 3 times thinking I got defective ones. Still throwing the code, I determined that either the throttle body is really gummed up, (Sprayed some carb cleaner but I think it still needs a good cleaning.)the plug is bad or there's a short on those wires. What is the best method to determine if there is a short, and how difficult would it be to replace the wiring?