New to the forum; first post. Thanks in advance for help.

I have a 1997 c40tlrv 40 hp 2-stroke, 3-cylinder motor. It has always been reliable and performed well. Recently, I have developed a problem where it will hardly ever stay running at idle. If I start it and put it in gear as soon as the advanced idle period ends, I can run through the midrange and at WOT no problem. Sometimes, after running for a bit, I can idle some and it will stay running. Usually, however, when I bring it down to idle it runs for a few seconds, gets slower and slower, and dies. Then I developed a regular pop out of the exhaust at low throttle. It was obviously missing and running very rough when it would idle.

I can run it on the muffs at the house with the fast idle lever raised about 1/3 of the way and it will stay going. Any lower and it dies every time now.

First, I replaced the fuel pump (and gasket behind it) and the motor side and fuel side ball valve fittings. I am running with a good hose on fresh gas out of an extra can at the house. It is hooked directly to the pump in case the problem was the filter. When I initially replaced the fuel pump (it was compromised), the first time I started it up, it seemed to run dramatically better and the regular pop from exhaust went away. However, it still runs rough and will not idle. Still have to use the fast idle lever to keep it running.

Checked compression. I have (from top to bottom) 95, 95, and 90 on a dry test, and 100, 95, and 105 on wet test.

Checked spark. I have 7/16" spark at all three plugs.

Next I cleaned the carbs. All seemed really clean inside, but bottom carb may have been slightly clogged. Put back on and although it still ran a little rough, I got idle back. It was late, and I figured after I did a link and synch the next morning, all would be well...

Well, the next morning I followed the service manual instructions to set the throttle linkage (pointer on cdi and full retard and advance screws). There was a small adjustment made. Next synched the carbs (closed all butterflies, tightened adjustment screws, then set roller to hit cam about 8 degrees atdc).

Now it wont stay running at idle again.

Other symptoms than what Ive described:

Seems like a bit too much oil pooled in the throat of carbs, especially lower one, since I have only run it about 30 minutes since cleaning them. There is no oil injection, so it isn't that.

If I pull the plug wires, all drop the RPMs, although it almost sounds better on two rather than 3 cylinders. If I put my hand in front of the carbs, RPMS drop noticeably on middle and bottom, but it will choke out when I do the top. The top also seems to have significantly more suction, just by feel.

So... any suggestions where to go next? I don't have a timing light, so that is the one thing I haven't checked yet. But, it doesn't seem like it could get that far off unless the CDI is just toast. I have seen a test for it in the manual. Would this tell if it was jacked up in terms of intermittent spark or timing, or just whether or not it works?

Also, what are the hoses and check valves on the starboard side of the crank case? They run behind the CDI and starter mounts. I assume these are recirculation hoses for emission purposes? They look kinda rough. Could this be the issue if there was a leak in one of those?

Does this sound like it could be bad reed valves in cyl 2 and 3? Gasket?

Thanks again in advance. Sorry about the long post... At this point any suggestions would be much appreciated