After sometime time consuming efforts I have found no fuel problems. no spark problems and good compression. So I moved to getting out my meter and checking sensors. On my map sensor 3wire plugne ground, 5v from pcm, and a voltage reading from map sensor to pcm. I have no voltage coming from the pcm, so also no voltage going back to pcm. On my IAC sensor 2wire plug ground and 5volts from pcm and Iac makes adjustments to the volts for the pcm and I have no voltage there also??? would my pcm be going out and does anyone know how to test the pcm? thanks for any help and your persistance on sticking with me on the pain in the rear blazer.

 

It sounds like the 5V reference feed from the PCM has either failed or otherwise is not getting to the sensors which use it (wiring problem).

 

I have this same exact problem but I am also getting code 23 sometimes from the computer... I am going to check all the connections and see what happens.
Did you ever fix the problem?

 

now that the weather is warmer I've had a chance to resume work on the blazer. I pulled my distributor out and did the ohm test the book called for and the pick up tested bad. i whole distributor was so rusted ihave no clue how this thing ran in the frist place. anyways i bought a new distributor and i am currently trying to set the timing and can anyone tell me where this distributor ignition wire is that needs to be unplug....to answer ur question no the problem hasnt been fixed yet, but hopefully soon

 

The wire should be off to the passenger side of the transmission tunnel inside the truck. You may have to pull back the carpet/sound-deadener a bit to see it.