Try getting some used parts at a local car parts yard.
Maybe an idle air control valve, mass airflow sensor, throttle position sensor (or the whole throttle body!).
Parts are cheap. Labor… well we know what that costs. maybe you should try and find a local person through FSWERKS or FOCUSFANATICS web forum. Some people on there are really helpful and its a forum only for ford focus people - and they have a buy sell trade section where you could post something saying you are looking for “lots of sensors for a duratec engine / 2008 ford focus”
YOU CAN DO IT YOURSELF - or at least some of the easier things.
Get a repair manual for the car, chilton and haynes are popular. replace a few of the easy parts - and if it runs better / worse, note it.