Were is the egr position sensor on 99 Chevy s10 2.2L?

The 1999 Chevy S10 2.2L engine doesn't have a dedicated EGR position sensor. Instead, the Exhaust Gas Recirculation (EGR) system uses a EGR valve and the powertrain control module (PCM) monitors its function indirectly. The PCM uses other sensors (like manifold absolute pressure and engine coolant temperature) to calculate the correct EGR flow and won't find a dedicated sensor for the EGR position itself. If you're having issues with the EGR system, you'll likely need to look at the EGR valve itself, its vacuum lines, and potentially the PCM.