1999 Mercury Cougar. Engine Size : 2.5 v6

Question: When the air temperature drops below 35 degrees it runs rough wont idle right. Ive changed fuel,air filters, mass air sensors spark plugs and wires.

Answer:If you have a check engine light, get a scan of the codes. Sounds like your Mercury has a vacuum leak. This causes a lean condition in the engine because there is too much air and not enough fuel going in. When the temperature gets cold out, rubber seals shrink and cause a vacuum leak. When the engine warms up, the seals expand and it runs better. Most common is the intake manifold gaskets.

Another common cause is that the idle air intake valve is gummed up. The valve cover ventilation system on this car vents directly into the the idle air intake. This causes oil blow-by to plug the line. In the summer the oil and gunk are thinner so the valve moves properly. This valve is on the back of the intake manifold. Either have it replaced or clean it out with some carburetor cleaner. You will need a new gasket for it since after removal the old one will tear.

Ford Explorer EGR Sensor Location

2001 Ford Explorer Sport.
6 cylinder 4.0 liter
Warning lights = check engine light
Computer codes = EGR valve
Repairs for this problem = replaced EGR valve but code is still showing up as EGR. 
question = wanting to replace sensor but don't know where it's located at. The part they gave me at Autozone does not look like the part that is on my vehicle. Not sure we are looking in the right spot, can you tell me where the sensor is located please?  thanks much.