the reason why you had this flickering problem was that you had too much power on the RFPD in reflection of the PMC. You already saturated it.
I also reduced the RF power as the error signals were not signals anymore, just spikes.
my new settings are:
RF power : 3.0
Phase : 2.5
PMC Gain: 14dB
reduced laser power to 40mW. Transmitted power is 32mW .You have to exchange the output coupler mirror in front of the RFPD in order to increase the power. I think 32mW is enough, it's something like 13mW per cavity.
Ok, I'll find another output coupler mirror and replace the current one, and make sure that it will not saturate the RFPD.