Long distance diagnosis for my brother. He has an 89 Ramcharger with 318, throttle body injection. It runs great when cold, but after it warms up for about 5-10 minutes, it gets rough. It feels like it loses power and acts like it is flooded or not getting fire properly. Then it quits, and will restart and run a couple minutes, but very rough. He says it shows code 37, but always has shown that. My first thoughts coil wire, coil, distributor cap/rotor. Any other thoughts before he starts replacing parts?