FIXED

Sorry its taken so long to respond as weather as held us up a bit. You were right David we did drain tank and yes there was diesel in with the petrol. Strange as when we removed injectors it smelt like petrol. Car belongs to a elderly lady and she says she has not put diesel in but some one did. Also where it had been trying to run on a mixture of petrol and diesel it has damaged the cat.

Thanks again for your help.