1985 2.3 EFI, runs better with o2 unplugged?

[pokeyYJ]

Any thoughts? My 85 has a slight misfire at idle, I replaced plug wires and plugs. Still had a slight misfire, like 2-3 misses every 20 seconds. Unplugged the o2 on a whim and the truck seemed to run better. The perfume owner said he had replaced the o2 recently. Thoughts?