2003 Mercedes Benz CLK320 car engine turnned off after 30 m

After using car for 30-40 min the engine turnned off when I stoped pushing the fuel. Then when I park (P) it returns to work normally when I switched on again. But the same wehen stop pushing the fuel it turned off again. Even if I re-start it and keep it at the park position the same after few seconds turned off. But for short trips like 10-15 min its ok & no problem happens. But when its happens I neeed to park the car for at least 3-4 hours to wor normally again for just short trips.(10-15min). Mor than that 30-40 min, I faced the same problem even if the speed were 80km/h & stop pushing the fuel the engine turned off!