Saab 9-3 2.2 tid - fuel / engine problem - suby_1996

Hi, I am experiencing problems with the above, all of a sudden the car has developed a fault (No fault lights are on the dashboard) when traveling along the car looses power then returns to normal, Under acceleration same problem, pulling off same problem, it lasts for seconds and is a continual problem, Feels like a fuel problem, i do have thought might be a sensor problem as it feels like it cuts the engine and instantly return to normal as when it is fuel starvation the process is usally longer than seconds, In netural the car revs upto 3000 rpm and then sounds like its miss firing but then if you try it againn it will be normal and go round to red line so very hit & miss