I have a 2000 Taurus with a 24 valve dohc engine and it is missing.

Do you have a check engine light on? If so, post code on here to help us assist you. It sounds as if you have an intermittent firing problem which can be a spark plug ignition coil or the plugs themselves. Need more info. please.

check plugs wires dis and so on

I have the same problem. AC load makes the engine idle rough worse. Took it to a shop. Found out more than likely I have a sticky valve in the engine. Possible you have the same problem. I had all the possible vacuum issues checked all passed.