I am back to thinking it is a blockage in a carb. I cannot find a vacuum leak. I have tried carb cleaner and propane. I am 99% sure it isn't an internal intake gasket leaking. No change when I put propane into the crankcase, but more importantly, no smoke. I would think it would smoke like a freight train sucking oil into an intake port.

The carbs are fresh and all of the fuel lines are new, but I suppose something could have made it past the fuel filter or something came out of a fuel line.

FYI I have had high readings like you describe just before the O2 sensor takes a crap, If you have a new sensor put it in and calibrate it and try to see what it reads, obviously shut down if it still reads high. I have been fooled in the past by this, more so if you have any amount of reversion in the exhaust. The Cough/Hiccup could have gotten the sensor damp. Again just another thing to investigate.
Good Luck, keep us posted

will do, thanks

Check the needle and seats too. I've seen where a piece of crap gets stuck in the needle , and blocks fuel flow partially. It can still keep the bowls full at idle, but once underway and the fuel demand goes up, the bowl goes dry.

But idle from 14 to 20:1, I don't know.

Joe, just thinking but did you completely rebuild the carbs? If so maybe you did not get the base to throttle plate screws on the bottom tight enough and are leaking air slightly there. Gotta be something small but weird in my opinion.

Do your datalogs show anything interesting from the map sensor readings?

Also, the pv not opening/ not opening wont affect idle afr. Now if it blew the diaphragm, it would go rich at idle.

I didn't have my laptop with me at the lake

one thing, you said you are using the intake for the PV vac signal...that will see pressure under boost and close off power valve, need to get vac from under carb above blower I think.