Thanks @RWB, I saw your post too but it looks like you are using a 2wire fan and controlling the speed by sending PWM signals over the load. I am trying to use the dedicated speed control pin of the fan. But maybe this is a dumb idea and I should just use your approach. And I do have a 1k R on my MOSFET.
Did you end up keeping in the diode? None of my MOSFET rigs have flyback diodes but none of them (except this one) run motors.