had same issues
I just got through dealing with the same issues on my sons 95 929. we lucked out and found the mazda shop repair manual the only manual i've seen for 929s. we were getting the same code 16. I lucked out and found a 929 at the wrecking yard and grabbed the egr with sensor and the 2 vacume selinoids. I checked the egr and it seemed to be working and the sensor seemed to check out so i switched out the orignal vacume switches with the wrecking yard ones and that cured the problem. I don't know where they might be avaliable new but if u can get ahold of another pair of switches used try them out and see if that helps .. good luck
