Volvo idle began to race a month ago, I found and reaplaced a broken (intake?) hose. this seemed to fix the problem. Now She is cutting out periodically. This is similar to the symptoms of a shot in-tank pump (which I replaced a year ago)however the cutting out seems alot more unpredictasble (sometimes more, sometimes less sometimes driveable sometimes not). I can hear the pump fire up when I turn the key. Is this a fuel, or an air problem or something I'm missing altogether?

Thanks.