Removed PC3 & reinstalled O2 sensor. Checked MAP vacuum line, they're all clear, checked fuel tank vent, it was partially clogged but I cleaned it out and its open.
STILL CUTTING OUT
In fact I got stranded down the road from my house So from what I remember that code is either the kick stand down while in gear, or just ECU error.
Anyone have any other ideas? is something just flat out wrong with my ECU??
I suppose an ECU can be faulty, like any electronic gear. Maybe somebody here has a spare ECU that they can lend to you, for a test. With the Ivan re-flash project, I'd expect there to be a few extra ECUs around the FJR world now. The (real) electronics shops can sell you a can of aerosol freeze spray, which can cool down the ECU to frosty temperatures. A hair dryer can warm the ECU to hand-comfortable temperatures, safely. These temperature changes should NOT
affect the engine operation in the shop. If that does happen, then the ECU definitely needs help, or even a replacement.
Since the problem does not happen when stopped, only on the road, I would want to start the bike and use the clutch (in gear) to make the bike surge forward a few inches, and repeatedly. If there is
water in the gas tank, you may be able to get it to slosh around in there, enough to cause the cut-out problem in the shop.
Back in the day, I once made a water-oil separator (like the old Ford tractors had for gas, but tougher) to keep any water in my oil tank out of the 2-stroke oil pump. The Yamaha dealer wrote me off as a nut. (I wouldn't argue the point, even now.) His opinion changed, when I showed him later that it was working; the separator soon had an ounce of water in it. Wish these bikes had a loop of clear fuel line (and visible) on the bike's gasoline supply system, these days. It would prolly cost an extra two US dimes for each bike, though.
Hang tough, there. Keep us posted.