I have a 95 blazer 4.3 2wd. On my way to my parents house it started to almost die at idle. It would stall if you took it out of gear. But in gear (od) it would rev over 1000 and under 500. In neutral if you revved up to 3000 and let off the accelerator it would slowly go back down. I was going 80kph (50 mph) for about 25 min. then pulled into town when i noticed it. Also when you stopped from say 25mph, it was really difficult to get the vehicle to stop. ie since the motor slowy decelerated in neutral i'm assuming that the engine was still pulling hard when i tried to stop. It doesn't seem to be ignition or fuel related. It doesn't miss, it pulls hard. I was loaded and had a canoe on the roof and i could go up a steep hill at 60 mph in od (1500-2000) rpm depending on whether the torque converter was locked up. By the time i got all the way to my parents house it was working fine in their town. But I stopped in another town on the way there and it did the same things as the town that was 25 min out. It threw a code, but my scan tool is 700 km away!! Sorry the post is so long. I tried searching but didn't find anything quite the same on the forum. POssibly egr? I figured a vacuum leack big enough to screw up the idle wouldn't majically go away.
Thanks,
Wally

 

I would pull the IAC valve (near the throttle plate in the upper plenum) and clean it and the bore it goes into very thoroughly. Also remove the intake duct work and clean the throttle body very well. The throttle body on the CPI motors is part of the upper plenum so it can be fun to clean without removing the entire upper plenum.

While you are doing that, disconnect the throttle cable and see if there is any tight spots in its travel. Inspect the cable itself for signs of being kinked.

 

Thanks
I'll try that later today.

 

I cleaned the iac. It didn't make the problem go away right away. but if i unplugged the iac wires the problem went away. Last night when i went out the check engine light went out after a restart, and it drove fine in town. I'll have to check what the code was when i get home.

Thanks again,
Wally

 

Let us know how it goes and what the code was.