hi guys,just an update.went back to ford yesterday.They checked computer they had installed last weak.It apparently showed the air temp sensor not working correctly.
What do you think? Is this a true possibility for idle and bad mpg??
They will install new on next weak,hope they are right.I will keep you all posted with the results.

 

Yes it could be a problem.
If the PCM thinks the air is a different temperature than it really is it will adjust the way the engine runs to how it should be for the wrong temperature.