Got a problem with a fiesta 01 1.6
it won't hold idle swinging between about 400 and 1000 rpm, almost stalling. at the lowest point of the revs theres a loud sucking noise around the TB area. it's also down on power

Any ideas?

air leak or aux air valve,stick a length of hose in yr ear and follow the sound

As above -- it helps to use a length of tube as stethoscope also check all the hoses for splits.

With Fords it is also a good idea to clean the throttlebody, idle control valve and egr valve with carb cleaner.

Clean the idle control valve and make sure the throttle body is sealed.