Hello Mercury forum, looking for a little input on a problem with my 96 Cougar. Car has 218000 miles, 4.6 litre V-8, is in excellent shape for its age. Fires right up and idles fine (meaning it will sit there and run with out giving the motor any gas). My problem is that when the car has been sitting for a few hours and the engine temparature is cold, when you first start it and let it run it will start to run rough, however if you just let it sit and get to operating temp it runs just great. I was wondering if anyone has experienced a similar problem and what was done to solve it. My thoughts at this point are maybe one of the sensors (i.e. oxygen), wires have been changed, and MAF sensor has been cleaned, but I am looking for any input anyone may have.

 

Check vacuum pressure at the intake manifold?

 

Good morning and thank you for the tip CNS420, I will check that as well.