Where is egr valve on 99 4.3l Chevy blazer?

The EGR valve on a 1999 4.3L Chevy Blazer is located on the passenger side of the engine, near the back. It's usually attached to the intake manifold. It's a relatively small, rectangular valve with vacuum lines connected to it.

However, the exact location can vary slightly depending on specific engine configurations. It's best to consult a repair manual specific to your year and model Blazer, or use a diagram for your exact engine to be absolutely certain. You can often find these diagrams online by searching for "1999 Chevy Blazer 4.3L engine diagram". A visual confirmation is always recommended.