After weeks of changing parts and scratching my head, I found the cause of my random misfire. I went to change the harmonic balancer and crank sensor, and after removing the balancer, I found that the screws holding the reluctor ring on were loose. I applied Loctite to the screws and retightened them, and like magic, the misfire was gone. Took about 30 minutes. This is a free check, and beats spending money chasing a ghost. I have seen a lot of people struggling with this problem, and I sure hope this helps someone. Wish I had found it sooner.