Picked up an 03 TB LT EXT w/4.2. Was going to use it for parts but it might be better to put it back on the road if possible. Good interior and exterior. Starts instantly, but runs very rough, the engine shaking like crazy. Can move itself, but would not want to take it out on the road. Codes point to both the crankshaft and camshaft position sensors. Where should I start? Examine plugs & coils and do compression testing first? Or replace those sensors.