If you have another silver washer like the one that's under the white plastic spacer on the needle, then you could move the clip to the third, and add the extra washer so there are two under the white spacer. It'd be a half a step leaner then where you are now. I think, that when you have the lag, and it plays catch up, its a sign of being to rich, but that's normally a main
issue, and where you are, the 170 should be okay. If you don't have an extra washer, you could try a 167.5 main, and leave the clip in the 4th and see if that makes a difference.
Most of the tuning, tends to encourage you to work to the lean side until you have issues, and then back up to the last step.