At wide open throttle (button under acc. pedal depressed), the O2 sensor is indeed offline. When my O2 sensor was going bad, but prior to illuminating the "check engine" light, at 1/2 to 3/4 throttle the car would surge a bit, just noticeably.
Frankly, your symptoms sound like bad distributor caps-the M119 in your car eats the distr. caps & rotors every 50-60k. I doubt the O2 sensor would make it feel like a miss.
"If everything seems under control, you're simply not going fast enough" --Mario Andretti
1995 E500 street car
1986 Porsche 944 Turbo S track car