914 Barely Starts and Won't Get Above 780RPM (Video)

It looks like my installation has airbox pressure, but not a manifold pressure sensor (see attached pics).  So, I'll look into that.

But, that doesn't explain my current issue as I've been flying with the current setup just fine.

You say it's likely a fuel starvation issue, but you can see in the video I have proper fuel flow (exactly what I've seen on prior starts) to the right carb (the flow sensor is right before the right carb) and all the EGTs are coming up.  And notably the left cylinders (2 and 4) EGTs are just as high as the right cylinders.  So, is fuel really the issue here?

I've started the process of cleaning the air filter and will reinstall that tomorrow.  I'm doubtful that'll make a difference but doesn't hurt of course.

I wish I had a Rotax mechanic right on the field...  

I just spoke to the Chief Test Pilot at Sling Aircraft and he said he'd pretty sure he knows what the problem is: A stuck turbine.  He's seen it before, sometimes caused by a hot shutdown, where the turbine gets stuck.  With the turbine stuck, the engine is starved for air which explains the stuck MAP indication.

He said to try and free up the turbine and try again...  I'll let you know.

There is a very good video on this website that details the turbo system. Watch it and you will be well prepared to start looking at your turbo.

Looking at the second picture I see on the cross over tube the port for connecting a manifold pressure gauge is open and such a vacuum leak will cause rough running.

It's not open.  It's securely plugged.