maybe check the brakes for wear & bleed 'em. thats another good one. grease the zerk fittings.

 

Well this seems to be going in the wrong direction. Since I had trouble (couldn't do it) changing the spark plugs I took it to a shop.

Replaced all six plugs
replaced PCV
replaced fuel filter
SeaFoam through the PCV (this was several days before replacing plugs, ran fine)

Now I have a weak idle. It idles around 600 to 500 RPMs. Which is low enough to cause a rough ride. I'm going to check to make sure all of the plug wires are on good. It runs fine when driving, but it has a mild shake when stopped. For some reason I thought with 80,000 miles it would be a good time for a tune up, guessin' now that I was wrong.

 

If it seems like it is idling low, you may want to pull of the throttlebody and clean it. The IAC (idle air control) valve is on the drivers side of the TB at the back. Pull that out and clean both the pintle and the mating surface inside. You might want to use an old tooth brush to clean out the passages.

While you're at it, now might be a good time to cut the baffle off of the throttle plate. I noticed a pretty good increase in throttle response with the baffle cut off. You can't just drill out the rivets that hold it on, you really have to cut it off with either a dremel or a careful hacksaw. Just cut the horn part off.

 

Mine idles just fine at 550rpms.
Did you get the cap and rotor changed too?

 

Once all warmed up, mine will idle around 550-600rpm, but when cold, it idles around 800-900rpm.

 

I did not change the dist. cap and rotor. This week I'll clean the IAC.

I have two seals (front pinion seal and transfer case seal) that are leaking and need new drivers door pins & bushings. My shop said they would do both for $210 (includes parts).

 

It might idle better once you change the cap and rotor.

 

Thanks Hanr3, I might have to move that up the list.

The old plugs looked pretty good. A fair amount of carbon, I'm guessing, on the tips. According to the Blazer computer the MPG are going up!! So I'm glad about that. The idle isn't real bad, you can just feel it choke itself off (guessing, but that is how it feels) and RPM bounces between 500-600. Seems to have the slightest hesitation upon throttling up and then it is fine (as when pulling away from a stoplight).

I certainly appreciate the input and advice. While I'm not much of a mechanic I enjoy trying to do the tinkering myself. Wish my success rate was better.............

The service manual says after cleaning the IAC to "re-program" the idle setting. It says to do this by starting the Blazer for 20 seconds, shutting it off for 10 seconds and then restarting. Ever here of that?

 

Honestly, if you have carbon deposits on the rotor/distriburator cap, it will have a rough idle. Not enough spark getting through.

You could spend time on the IAC, although I think you would have greater success putting on a new cap and rotor. So much so, that it would fix your problem and you wouldn't need to worry about the IAC. The IAC either works or it don't. EGR is a possibility, however I would start with the cap and rotor. They are very critical parts of the ignition system. I'd be willing to bet a beer that changing the cap and rotor wil fix your problem.

 

Given that he hasn't even looked at the cap/rotor, I'm betting that is where the problem lies. Cleaning the IAC valve is never a bad thing and won't hurt anything.

When I get home from work today, I'll get out my old cap and rotor and snap some pictures to show you what a marginally bad set looks like.