I have a 1992 Chevy S10 Blazer 4x4 Vin: z 4.3L

When it is at operating temperature and I stop at a red light or stop sign the idle dies down real low and and almost dies on me. It like dies and then comes back and makes the vehicle move forward a little. I have replaced the map sensor, throttle position sensor, Idle air control valve, egr valve, egr vacuum seloniod, fuel filter, and fixed the loose vacuum line connections. and still no luck. spark plugs, wires, and cap were changed about 3.5 years ago. i run 91 octane in it

It also has some bucking to it when i let off the gas. it doesnt do it all the time

 

How long ago did you replace your EGR valve? These are notorious for getting dirty and causing problems like you describe. Sounds like it may be time for a fresh tune up as well.

 

remove the throttle body and clean the passage ways,including the iac tunnel with a toothbrush. good ol brake cleaner works for this.

 

I agree with cleaning the throttle body.Also spray some WD-40 or carb spray around the bottom of the tb where the shaft goes through and make the theres no vacume leaks there.

 

I replaced the egr valve about 3 months ago

 

All good ideas another idea, stop buying 91 octane gas, its just wasting your money, theres nothing wrong with the 87 that's called for. 91 is for high performance stuff, you don't get high performance by filling with it.

 

Have you checked ignition timing with the EST wire disconnected?

 

I had a similar problem with mine after it sat for a while without being driven. my distributor itself was rusted out on the top and kept the spark from firing on number 3 and 5 cylinders. it wasn't until I pulled the entire distributor out that I could see it.... this might not be your problem, but your problems sounds an awful lot like me.

 

Hope he fixed it since 2013...