when you unplug the lambda you should notice a loss of fuel economy (if the lambda was working) and usually the idle rpm will be affected (unstable) when warm, but as T14086 says the ecu has stored default parameters that are used when a sensor returns no signal, and idle management would still be possible using the rpm sensor, so a faulty lambda can go unnoticed.
when you have a faulty lambda that is not returning a probe signal, you would expect unplugging it to have no effect because the ecu would be using the default parameter already. if you do notice a difference then it suggest the lambda was working. it can take some time to notice a loss of mpg.
unplugging the idle speed control actuator will mean the control valve stays in whatever position it was in when you unplugged it (open if the engine was switched off at the time). that will only have a noticable effect on idle rpm, specifically the cold idle if you disconnected it with the engine switched off.
i dont know what the other sensor was, but it doesnt sound like the MAF.