[Cdnone1]

I have searched and read a lot on this subject (maybe too much ) so I need a fresh perspective.
I have a 82 SC
It has been running great. I gave it a tune up, new plugs, filters, rotor, cap, fluids and it ran great.
I was running the car without an O2 sensor and decided to hook up a new one about a week after the tune up. At first the car ran great though it seemed to search for idle and a very light stumble or hesitation at times. Last week it started to stumble when started cold (OK cold for LA 60 degrees) like it was running with a couple of plug wires unplugged, backfired a couple of times, but ran fine when warmed up.
A few days a go it started rough and stayed that way. Like it was running on 4 or 5 cylinders. I can not see anything amiss and the car ran great when I parked it.
It starts fine but runs like crap, like it had a cracked air box. There is a pop off value on the air box and it is well seated. I have looked at the rotor, cap and looked for obvious air leaks, including looking for a crack in the air box. I can't see anything wrong
I was worried after years of running without a O2 that might be it. I unplugged the O2 FV relay and it made no difference whether it was plugged in or not. I replaced the FV O2 relay, still runs like crap. I disconnected the O2, still runs like crap.
Any idea's at this point? Maybe Lambda. It was running to well when I parked it for a major vacuum leak to develop just sitting in my driveway for 2 days
I can't keep it running to check for leaks with carb cleaner by myself.
What do you think happened and where would you point me next?
Anyone in LA like to come by and look listen and give me some idea's?
I would appreciate a specific thread if anyone knows of any
Thanks
Steve