alrite guys

i've got a s2 which has got a weird running problem can any1 help???
i was driving along a couple of weeks ago a nd started jumping so i pulled over and it cut out, wouldnt restart straight away so left it 4 a while, finally got it going. got it half way home and it just died luckily had enough speed to roll home. since then havent been able to get it started. i've changed fuel relay, metering unit, rotor arm, dizzy cap, i'm getting spark and still no joy until yesterday when it just fired up!! left it ticking over 4 bout 20mins thought id take it up the road done bout a mile cut out again, wouldnt restart, so i struggled to push it up the road stopped 4 a breather tried it started bingo!!!!! drove it home left it outside my house 4 about an hour ran fine so i thought lets try again done bout 10 miles ran like a dream.

the only thing is i still dont know what was/is wrong with it any1 got ideas????????????

any advice would be apreciated.

thanks marc