What causes "dieseling"

Ran out of weekend and have not had time to mess with it more because of overtime at my office job.

I have a 3 day weekend coming so I'm planning to work on it more. I'm going to lower the idle and then I'm going to take the time and find TDC and mark the balancer and try timing it again.

Also I have some more tune up parts on order.... Shame you cain't just walk into a local parts store and get slant six parts over the counter anymore.