Johnson/Evinrude Marine engines - 2000 Johnson 150HP outboard over-heated

I have a 2000 Johnson 150 hp outboard motor. Last week, it over-heated, I shut it down right aw..

I have a 2000 Johnson 150 hp outboard motor. Last week, it over-heated, I shut it down right away.
All the cylinders checked good for compression. Installed new water pump, & spark plugs. It idles great, but, when I put it in gear & give it throttle, it "loads-up" and conks out!
Any ideas on how to correct this? It has "optical ignition system".

. Since you had the lower unit off, check the shift interrupter on the starboard side of engine.
This kills the engine when you shift in/out of gear and if misadjusted it will kill one complete side of the ignition when shifted resulting in a bog /no power problem.
You can check it real quick by unplugging connector on switch and if runs ok adjust it. Do not run it disconnected as it puts excessive wear on cable and clutch dog/gears.