The 1986-1991 EGR Valve is located at the rear of the intake manifold. Exhaust Gas Recirculation limits emissions by re-burning some of the exhaust; this process is also critical to proper engine performance and efficiency. A sticking EGR Valve will make its self known through a number of quite noticile driveability issues. Typically a faulty EGR system will trigger a dash warning light and a telltale diagnostic code.