The easy quick test for the lambda control unit is to warm up engine to normal temp and then unplug the O2 sensor from the wire at firewall. Now grab the wire on harness with a bare clean hand and then touch clean metal for a ground with your other clean bare hand. This should make engine run rough as frequency valve duty cycle changes (can hear this as frequency valve buzzing getting more intense) to enrich fuel mixture.

Now grab battery positive post (won't shock you) and the engine will run bad again as the lambda control unit leans mixture, frequency valve duty cycle will get less and the frequency valve will get very quiet.

If these two range tests are successful then the lambda system is okay and the base CO adjustment should do it given that you have determined that the O2 sensor does range 0 to 1.0 V.