From memory I think there is quite a bit on these in the archives, might be worth a look.
Going back to your origional post. Inj pulse strikes me as being a bit wide. If it is then the extra fuel is being commanded by the ECU even though the O2 sensor is stuck high. Maybe someone here can tell you if that pulse width is too wide or not.
You have already tested the coolant sensor and I think the only other sensor that will take priroty over the O2 is the MAP. Check the actual engine MAP with a vac guage. If you have a vac pump give the MAP sensor a healthy vac and see how the pulse width and gasses respond.
Check fuel pressure. Could also be a faulty injector.