I have a '91 S10 Blazer with the 4.3L engine. Sometimes when starting it acts like it is running very rich and stumbles. If I rev the engine a couple times, or drive briefly in low gear and take my foot off the accelerator it will settle down and run well.
It also does this rough idle if I drive at high throttle for a while, then stop.

I have replaced the PCV valve (although the old one did not look bad).

Any other ideas? Clean the MAF? Others?

The car gets around 17 mpg with mixed driving.

Thanks in advance.

 

You do not have a MAF sensor so that is out.

I would clean the EGR valve. If this is leaking past, it can cause rough idle and an overly rich condition.

 

Thanks. I will check it out.

Mark

 

Where exaclty is the EGR valve on the first gen's ? Mines a '94, Im just curious.

 

if you run a quick search you should find your answer i know its been discused before and i beleive someone posted a picture of the EGR location also.