urgent help needed
fiesta rs turbo

car has some kind of problem and im at my mums with it atm,

its as if there is an air leak, poor idle, if idles at all, boost gauge was orignally at -20 now sits around -10-14 up n down now and then, runs poor unless on hard boost but backfires etc etc if u rev it

any1 have any ideas how to cure it?