1993, 4.3, CPI, Check engine light, EGR or O2 sensor???

[sandystream]

First things first, I have replaced almost all engine sensors and I am still stumped...NEW-fuel pump, fuel filter, fuel injection octupus, distributor, ignition control module, coil, cap, rotor, plug wires, plugs, battery, alternator, pcv valve, MAP sensor, idle air control valve, throttle position sensor, 2-engine coolant temp sensors, catalytic conveter and muffler.
Also, new Bosch O2 sensor...maybe I bought a bad one off the shelf, also a used EGR valve...I bought off ebay, not 100% if its the right one.

PROBLEM: Check engine light comes on, but most of the time if I accelerate sharply it will turn off, but comes back on in a few minutes, sometimes stays on, it comes on at any speed, even at idle.

SCANNER: 44 Oxygen sensor lean....this is the only code set.

Oxygen sensor reads: 74-150 mVolts, varies with throttle.

EGR Duty cycle reads: 0.0% most of time, but during accelerating it races up to 40-50%, but quickly goes to 0.0%, regardless of RPM.

Please, respond with any of your ideas or expertise, thanks.

[toivo]

check if you have 2 oxygen sensors.also replace you air filter.

[1ofaknd]

maybe your pcm wires are loose??

[sandystream]

Okay I went to Chevy dealer, forked out $100, he said I was not getting 5 volts to O2 sensor and that PCM was bad ($240 part + $180 install). I said no thanks, I went to auto store, new PCM $96 + installed myself. But, just as I suspect, NOT the problem, more wasted $$$. Even though O2 sensor is only 6 mos old, I will put in another and let you know what happens.