My 1999 115 HP Johnson Outboard runs great at high speed. It idles smooth, but the longer it idles, the rpms continue to drop until it shuts off. The only way to keep it running at idle is to continue to choke it and I have a callus on my thumb from choking it so much. I removed 2 of the 4 carburetors and did not find any trash. The only thing I can find is on one carburetor the adjusting screw is out 2-1/2turns from the seated position. I have not touched the adjusting screws on the other 3 carburetors.
