at a quick glance the o2 sensor seems very erratic and isn't a nice looking graph... i'd suggest trying another o2 but this isn't the main problem, it may just be poisoned from the excessive fuel. (once running correctly it may sort itself out as it burns all the excess off but if it's old replace it)
page 5 of this pdf, examples of normal & abnormal o2 voltage readings
http://www.autoshop101.com/forms/h37.pdf
even @ 4% tps position the o2 remains high at 900mv for a long time, the ecu is trying to reduce the fuel being thrown in going by the BLM but it's just not happening.
If you still have that spare car/engine try changing the injectors and fuel reg over and see how it goes then.
Plugs and leads in good condition, wouldn't be the first time i've seen an old faulty lead or 2 allowing to much unburnt fuel going through the engine causing issues with o2's.