I have a 90 mercury sable, 3.0 engine, 53k orig miles. It started to choke out, stall, backfire. I put a handheld on it to get the codes. It came up with map sensor, throttle position sensor and EGR valve. I can't for the life of me find the egr valve. I know what it looks like and where I'm supposed to see it coming off the manifold. Is it under the plastic cover on the the throttle body/cable?

 

I went to the ford dealership, parts dept, and asked where it was, and found out that my particular car did not come with and egr valve. It actually has a flat metal plate where an egr valve would have been mounted. Turned out to be the tps sensor and map sensor. I changed the sensors, and the car started right up.