You will get a Lambda light if you disconnect the BCS and to be honest, it wont prove much. It does sound like the BCS to me as you had a bit of a symptom 500 miles back and then it cured itself. That could have also been a sticky actuator. I would wack a MBC on or a donar BCS and see if that helps then go from there.
Good luck
George.
PS. I don't 'track' my baby, it's used as the safety car if needs be but I'd rather use someone else's brakes and tires. LOL
