Driving a mos with a dac
Ok, this behaviour out comes when a AOP drives a capacitive input like a mos' gate.
Added some filter and no more oscillation.

BTW, I found dozens of project like this on the net and obviously, like Finbarr says, using adc/dac to drive the system definitely not the best way.
A much better way (and an interesting way to learn AOP) is to let the AOP drive the mos with a loop back coming from low side current measurement. See here:
enter link description here