Our 2009 Ford Fusion, 4 cylinder, 2.3 engine has 79,000+ miles and would make an annoying clicking or whirling sound when the AC was on and I was told to replace the crank pulley, which an auto shop did. I picked it up the car and the whirling sound was gone but when coming to a stop light (with A/C) the car would shake. Called the Auto Shop and he said he also reset the engine timer and unhooked the battery and the car system should reset and to drive it for the weekend. When driving or at a stop light it shakes and now I noticed the RPM from 1000+ (when you first turn on) goes down to 700 (with AC) then when you drive it's semi okay till you slow down to a stop light or in park, of which it goes from 700 to 500 rpm with a near engine shut down but it catches and continues to struggle (it also has the same problem in park, reverse and neutral). I've been told it could the air intake, taking off the battery and wait 5 min (which I tried again..still the same). Then told it could be the radiator, AC pump, clean the IEAD (sp?), change air filter (which I did), could be the battery or a new engine mount that sits on the left side of the engine. I fix one thing to have more possible things to fix.