Just bought a 85 300 D turbo with 168k original for $350 and put almost 40k miles on it. I have to choke it to stop running. It got to the point it needed a battery. It cranks super slow and wont start. The starter spins the motor but not fast enough to kick it in. When I jump the starter from underneath, starter armature hits flywheel nicely and spins slowly. The same goes for the purple wires by the battery, run a jumper slow turn. Either neutral safety switch, ignition switch, or ignition tumblers. I am not a mechanic, but can do a lot thanks to this forum and you tube. How do I tell if its nss or ignition switch, or tumblers. Btw good compression and fuel delivery. Help plz.