I messed with some ferrite cores, beefed up my main ground to the motor, chassis, and battery, added some more capacitance to the 5v rail. All helped a lot but most effective was moving the coil grounds to the chassis instead of to the motor. But even with all this, I still seem to get the spikes occasionally. I'm fairly knowledgeable, but I'm floundering here. When I think I have it pegged, I'll switch things back to normal to check I've really solved it and sure enough, I get a random spike again.
I should add, before I tried to fix the problem, the amount of noise was far greater than what I get now. But I have a hard time believing I can't keep the noise down to a minimum level consistently and not stop the sync loss and RPM drop.
Screenshots are of a running tooth log, and megalog view of the rpm drop. Unfortunately I don't see any data while cranking of the tooth log. And I also added a screenshot of the scope. I'm out of ideas at this point...anyone who can help, I'd be greatful!