Standingwave

I Have a 1998 C200 Elegance, been 4-1/2 years of faultless driving... about 2 months ago it wouldn't start after being parked for a short time, now it drives for 15 to 20 minutes and just stops dead and turns over but won't start again. If I leave it to cool down it starts and drives but will stop dead again after 15 to 20 odd minutes. I changed my fuel pump and filter when it started 2 months ago, the MAF sensor was changed about 3 months ago, and I changed my battery 3 days ago... and still it stops dead... it doesn't throw any codes up so this doesn't cast any light on it... I've been told this is not an isolated issue but no one can say what exactly it is, can anyone help me please?