Thanks Guys,
Called dealer. He thinks it may be the fuel filter. I unthreaded the drain plug on the bottom and let some fuel drain into a mason jar. The fuel is clear but there was an initial batch of brown crude in jar - dirty filter? It starts up fine, no smoke idling or under pressure.
It may be a bad batch of fuel. I helped a neighbour farmer about a month ago and he filled the tank for me with fuel. I was down to about a 1/4 yesterday when all of this started happening. I put 20 litres/3-5 gallons of fresh stuff in this morning before going to my buddies' place. Barely got there and barely got home.
The dealer is coming by next week to replace the filter. I will drain tank - guess I will have to write off the fuel - and replenish.
Hopefully it is fuel. Other than that it has been running great.
TIA