300sdl wont' start or starts hard after it is hot. Glow plugs and pre-glow relay tests and works fine but isn't used when engine is hot. Starts so fast when it's cold that it scars you and runs like a champ for hours until you shut it off and try to start it. When it cools down it fires right up. New fuel, oil and air filters and new oil and battery. The car was in storage all winter here in MN and I started it about once a month. Started like a champ all winter. Even in the cold here in MN. I even took it for a spin a couple of times on nice days and clear roads. This problem did not occur when I put it away in Dec. Again, the car starts and runs like a champ all day long from a cold start. If I shut it off, it starts right away. If I let it sit for 20 minutes it either does not start or starts hard. If I let it sit till it cools down, it starts right now and runs like a champ.

Regards,

Bart