Have got a problem with my wifes car.About a month ago it stalled and would not start,we went back two days later to tow it to a garage. On arriving at the car i decieded to see if it would start.It did so i drove it to the garage,we got there and they said if the engine diognostic light wasn/t on they wouldn,t be able to get a fault code.so we left and since covered 368miles fully loaded and in all driving speeds around town and motorway,not a moments trouble.Until now ! the engine starts to stall when coming to a stop,when it does stall when starting its lumpy when revved, the last time two days ago it backfired and since run perfectly.Now we have taken it back to the garage they said the exhaust manifold was cracked and welded it. they put it on their diognostic mechine,and said its reporting large voltage fluctuations on the lambda sensor.They said we could try changing the sensor £100 pound and it may cure the fault, but i think it may be what ever sends the voltage to it,i cant afford a gamble of £100.what do you think,my wife uses the car for work and ferrying around our two and five year olds and i work away most of the time so not around to get them if it fails again.Any advice much appreciated.