Black soot is running very rich, lamda would not act up like this normally, it would do it all the time.
Iit's NOT going to show up, a faulty CTS as it has such a wide range , it is normally within range just not at the resistance it should be at the temp it should be.
Do you have another lamda to swap in there to try, old one maybe if not just get the metre on it when cold/hot and see what it reads.
Obviously there will be major problems if no lamda reading is getting to the ecu, so after checking at lamda if ok check at ecu, check also if it has a HEGO sensor the heater circuit.
tabetha