I'm new here and I've come in search of Blazer Expertise. My Blazer is a 2001, 130,000 miles, 4x2. In the last month or so, it has developed a rough idle when in park or stopped at a light. It acts like it wants to shut off and the RPMs drop about 100-200 when it occurs. It's been getting progressively worse, where in the beginning it would happen about once per stop, it's now to the point where it occurs constant and it feels like the truck will die. I've done all the prerequisite maintenance that I've read here on the forum to see if it would help, like changing cap, rotor, wires, plugs, cleaned the MAF and EGR, changed the air and fuel filters, and I've also Seafoamed. None of these things have fixed the problem. This morning, the SES light began flashing as I was driving to work. Any ideas?

As an aside, I've also got a slight transmission slip that only occurs only in 4th around 60mph...it's manageable, but not as big a problem as the idle issue.

 

A flashing SES light means you have an active misfire. You need to get the fuel injectors/metering body checked out - both the electrical connection and the injector system.

 

I've fixed the SES flashing problem...just a loose distributor cap. Still no idea what is causing the idle issue...