My car will buck and hesitate when trying to accelerate from idle. It will buck and hesitate, then sometimes surge ahead, or just totally bog. However, its fine with the O2 unplugged. I just tried installing a brand new Bosch O2 sensor, and I still have the same problem. Right now it is undriveable with the O2 plugged in, and unfortunately it is time for emissions testing.

Here is a little history of what I've done in the last year:
Ignition control computer (used, wiring harness checked good as well)
Hall sensor (used distributor)
fuel pressure regulator
replaced intake gaskets (cleaned throttle)
throttle position sensor (clicks off idle)
knock sensor
coolant temp sensor
AMM (rebuilt)
in-tank pump (new sock, hose)
main pump (new filter as well)
fairly new tune-up parts (air filter, ngk copper plugs, wires, cap & rotor)

I don't have a vacuum problem, and I made sure the flame trap was clean. At idle the O2 sensor wire read .9V and would not differentiate no matter what throttle position. I also did the test where you ground the green sensor wire, or add voltage to it to simulate a rich or lean condition, and it did fine.

The only thing I can think of is that I have a bad ECU. Where do I go from here? Thanks for any advice.

Jack H