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From what I been reading there is no egr on this engine.
The 1997 S10 Blazer has an egr (Exhaust Gas Reclaimer) valve. It also does not have a point distributor, it is electronic.
Check your EGR valve Check EGR valve
Up front, on top of the engine, next to the thermostat housing.
disconnect the hose and remove 2 bolts.
The EGR ( exhaust gas recirculation ) valve is located behind the throttle body on the passenger side.
The 1990 Plymouth EGR valve is located on the outside of the air cleaner housing. The EGR valve can be found on the back side of the housing.
The EGR valve is located in the center of the intake, at the front of the engine, between the alternator and the A/C compressor. I've added a picture of the location under "Links". It is titled "Picture of EGR valve location, on 1996 - 2001 4.3L (262c.i.) Vortec V6 engines"
Yes.
What engine???
Sometimes a piece of carbon will get caught in the EGR Valve. If is is hard starting, idles rough, and the brakes are hard, check the EGR Valve, it probably has a piece of carbon stuck, keeping it open.