0T749027 it's a 225 efi. I have had issues with it wanting to load up at idle in gear and die. This week it seemed to be worse than before.
I have an early Mercury DDT that I can monitor data and codes. I also have Smartcraft gauges that I monitor.

This motor will idle all day long as long as it is in neutral. When it is put into gear it will idle, start loading up slowly, and die unless I put it back in neutral or give it throttle.

Checking with the DDT does show the tps at .495 at idle. Press the throttle and let it go back to idle and it might be at .230 the next time. I know that is still within spec for idle but am thinking the tps may be a little erratic.

A month ago I discovered the wheel that operates the throttle cam was flat on one side so I replaced it. The air gap on the linkage is at .020.

The thing screams at full throttle and mid throttle performance is good. Just idle in gear.

Fuel pressure is in spec and does not leakdown. New plugs.

So, I ran it hard, headed back to ramp, and let it idle in gear until I got to the ramp and let it die on its own.

Pulling the spark plugs showed starboard cylinders dry but black sooty. Port cylinders were wet (not extremely) and black. This is indicating a rich condition.

I've checked the mechanical (pulse) pump and I was pumping the bulb when it was acting up and there was no change.

Engine temp was around 120 on the Smartcraft gauges and would drop to 65 degrees at full throttle. The water temp in the lake is 58 degrees.

A couple of weeks ago it was idling at the ramp on Tablerock and I got a high temp alarm. Shut the engine off and restarted it and the alarm went away. It didn't alarm the rest of the day and I idled out of a couple of creeks longer than what I did at the ramp. Again though, I would have to give it some throttle to stop it from dieing.

The only other thing I can say is when I put it back into neutral when it wants to die it will recover, and run at 1600 rpms and I would have to snap the throttle to get it to idle down.

New fuel filter, fresh gas, good oil, new spark plugs.

What am I missing?