Engine dies after warming up

My 1981 Bayliner 3270 has twin engine BB140A's with each motor sporting I believe are twin Solex P44PHN3's. The starboard engine starts up great and I run it at 2000 rpm during warm up, but after initially warming up to 170 degrees, I idle it down to the factory idle speed of 900 rpms. Then the starboard engine dies like it's flooding out. Immediately restarting is impossible until waiting for about a half hour, then same issue again after restart. If I was out on the water instead of tied up in my slip, I can shift into forward and set sail quicker to avoid engine dying on idle. Trying to leave slip is impossible with just port engine and rudder! Both engines have Pertronix. The timing is set @6 degrees BTDC. I even changed out spark plugs, and rebuilt rebuilt both carburetors last summer. I'm at my wits end! I'm hoping it's something simple I can fix instead of switching out manifold and carbs for an $800 single barrel Weber system! I tried to load pictures but some how they didn't transfer!!

Is it possible that the fuel pump is at issue? I am not familiar with your exact engines but on my 5.7, there is an electric fuel pump and when the engine warmed up, it would stop working. If I let it cool, it would fire back up. Also, what kind of choke is setup on the engine? perhaps it is not opening up completely when the engine is warm.

Thanks for the reply! The fuel pumps are mechanical and work fine, and there are no chokes in the design of the Solex side draft carburetors. But if it's the last resort, I can swap fuel pumps from port engine to starboard engine to see if it fixes the issue. Oh the joy of have twin engines during trouble shooting!