Thanks for the reply. I tore into it today and here are my observations so far.
Spark was good. Put a new plug just in case.
Fuel pump has good pressure and delivers plenty of fuel to the injector. My fuel pressure gauge didn't have the right fitting so I couldn't test the exact pressure, but I can hold my thumb over the hose fairly firmly and it will spray.
Removed the injector and inspected. Looked OK, but I'm no expert. I cleaned it with carb cleaner, air pressure and reinstalled. I connected electronics and tried starting it and it appears to spray a good pattern and what my untrained eyes sense as good.
Emptied fuel tank and put fresh gas (even though it had fresh before). Ensured I removed the anti-splash collar on the tank top when emptying all the fuel to make sure any bad fuel or debris was extracted. I poured everything into glass jar to inspect and didn't see any foreign debris in fuel.
Started it up and it seemed to run a tiny bit better, but it still stalls and runs erratically.
It seems to idle just great for a few seconds and then almost die or die. Same with riding, it seems to ride ok for a few seconds and then a sputter here and there. Stopping the machine and it will idle perfectly and then a few seconds later idle erratically or die.
Geez, why did I ever sell the little raptor 50?? That thing ran for 14 years without a hiccup and went through 4 kids and never missed a beat.
I'm basically at the end of my mech skills for this thing.