Nice job man, really fortunate outcome. Just hope you don't get another one like mine:
"What is happening is, there is an Actuator in the timing setup or VVTi (variable valve timing (intelligent)) and
well over 30% of the actuators made are faulty. they are failing to advance or retard the timing of the car properly to allow the car proper acceleration and cause RPM fluctuations like you were noticing. Toyota is actually rebuilding the entire top half of some customers engines because the problem is so severe, HOWEVER they are NOT informing their customers of this. I am good friends with my technician at Toyota and he said that he had done the job twice now, and that
over 200 FR-S have already been repaired for the issue and about 20 of those are already showing signs or problems again." --
Hotlava86