ka keeps stalling?

my ka is 1999. it starts up well first thing but if i turn car off, once at destination, it will not start again. i have to start it, keep it revving, then drive. as soon as i have to brake and take my foot of accelarator it stalls again. this can go on for a while then all of a sudden its like my ka has been pushed an got a bit of engery and it does not stall when i brake, until of course i turn it off again then the problem starts from beginning again. it has just recently stalled while sitting in traffic and does the same problem as the car has stopped and had to be started again. i have changed my fuel filter this made it ok for a day or two but the problem is back. has anyone had this problem before. i was just about to put this up for sale, its like it is punishing me for wanting to sell it!!! thank you