service engine light on code 71 on 1995 Toyota Corolla

I have tried to fix this and asked many people what to do . No answers. I know it's in the egr but where? there are so many things to check.

Asked by for the 1995 Toyota Corolla
Code 71 Exhaust Gas Recirculation (EGR) System Malfunction. Possible causes 1. EGR gas temperature sensor open circuit. 2. EGR Vacuum Switching Valve (VSV) open or short circuit. 3. Hose in EGR system disconnected. 4. Clogged EGR passage. 5. ECM. With the aid of a vacuum pump and applying vacuum to EGR valve while vehicle is running, vehicle should run rough or die which means EGR passages are clear.