I am experiencing an intermittent code 42 on my 89 k5 350 TBI. In an attempt to correct the problem, I have replaced the cap, rotor, plugs, and wires. I also set the timing (with the ECM disabled) to 0%. However, I will occasionally feel what seems to be a miss, and then the Service Engine Light comes on. Once that happens, the idle is rough and the engine feels like it is going to stall out at traffic lights.
I don’t want to throw parts at it in a guessing game now, so I look to you all for help. My next *guess* is either the EGR or Knock Sensor, but that is only an uneducated speculation. The reality is that I am unsure what to do next, and any help is appreciated. Thank you.