Hi, i have an old twin cylinder johnson 4hp outboard with a points system, one of those that the prop is in gear as soon as you start it (has no neutral gear) It starts with the throttle at least half open but when you try and turn it to slow down below about half throttle it suddenly dies. I have completely changed the carb but acts exactly the same and the compression isn't too bad. If anyone has an idea of the cause i'd be glad to hear it?