I don't think it's electrical. It could be low idle but with EFI it would probably be an idle air control valve issue. Sounds to me like a vacuum leak, and it's probably in the AC system. Not sure what year models have this, but some of the AC unit controls behind the dash are vacuum actuated. I know they were in my expedition. Could also be a line you knocked loose under the hood when making the other repairs. You could try the old carb cleaner spray around the hoses and intake manifold.

 

i have the same problem, i just dont put the a/c up more than 1/2 and its fine

 

This gave me my answer when dealing with the same issue.

http://www.fordification.com/tech/charging.htm