Autolevel won't work right until P and I are tuned. I am not surprised you are having trouble with the I gain at 0.
You set I AFTER you set P. Once you set P you can set I and I can impact P (allow you to go a touch higher). For an acro quad, you want the highest P gain you can set.
The first steps in tuning P and I are the hardest. You are going to make your copter almost unflyable on purpose so do this where you can chop throttle and not destroy your copter.
All of this is done in acro mode.
BE VERY CAREFUL HERE. If you go too high on P the copter can rise while you are reducing throttle and can easily gain 20 or 30 ft before you chop throttle and the copter falls. I have to go to P of 150 to do this, but you may encounter this earlier depending on your build. If you increase by 10 and don't get greedy, this is not likely to be an issue, but fly over soft ground just in case.
For aileron and elevator Set P gain to 30, P limit to 100, I gain to 0, I limit to 20. For yaw set P gain to 50, P limit to 20, I gain to 0 and I limit to 10.
The copter should fly but not well. Increase P limit on A and E by increments of 10 until you see the copter make rapid oscillations. Once you see (or hear in the motors) the fast oscillation, back it off by 2 or 5 until it is gone. My anycopter usually ends up with a P gain around 70 but again, I run Simon K.
Once you have P set, increase I gain to 50% of P. Mine usually end up in the 30s (Simon K again).
If after you set I gain you see a wobble in acro mode, reduce it by 2 and try again.
This should help lock in your copter.
Let me know how this goes and if you shoot video it will help us troubleshoot any remaining issues.