1999 Citroen Saxo CAR

Hi there, well the first day I bought my saxo when I was driving home I stalled then when I went to start the car it would start but then just die, to drive it I had to keep the revs on because if I didn the car would die again but after drivin like this for five minutes it would fix itself, I then drove it for about a month then all of a sudden this rattlin came from the front of the exhaust just behind the engine and stayed then the car lost alot of power and started making a funny whinen sound and wouldn rev past 4000 revs and had barely any power at all, can anyone tell me what happened.