Car stalling at idle

My car seems to stall when it is cold at idle, when I am stopped, or when I am just barely giving it gas like when I am backing out of a parking space. It also seems to do it when I am on an incline. It now also seems to be running a little rough and is getting poor gas mileage. I have changed the TPS switch, fuel pump relay, cleaned the throttle body and replaced a couple of oxygen sensors. I have no light on in the dash. Also, I am not sure if this is related or not, the temperature gauge started going up past halfway so I took it to a shop and they told me it was my radiator which was warm on top and cold on the bottom so I replaced that but when I replaced the thermostat, when the system was still full of antifreeze, no water came out of the lower hose, which I thought was strange. After replacing the radiator and thermostat the car does not run past halfway but my heater is not working which I think my need a flush but not sure.

Anyhow, do you think the EGR is bad and if so how would I replace it. Do I need to remove the plenum?

I would appreciate any help you can give me.