If what you're referring to as sub O2 is the downstream O2, that only tells the ECU if your cat is working correctly, no other function at all. So if your wiring that up causes an issue, it's you're wiring that's the problem, not the signal it's transmitting. You swapped ECUs when you did the harness I assume as didn't you say the stock had no terminals for it (non CA model)? Try moving the dist the other way a tooth as well if you didn't.

One other small correction for future searchers - the belt can't slip on the the crank/sprocket unless your keyway is sheared or partially sheared. Which is also a possibility I suppose, but unlikely. Crank is solid metal to sprocket inner race, tied in only by key, sprocket is solid metal to teeth the belt rides on. Vibration damper/balancer is glued onto front of fan pulley, nothing to do with timing belt.