Every morning the car starts up fine but only runs for 5 or 6 seconds and then stalls. After about 5 or 6 tries it starts up an runs fine all day starting up immediatly on demand. Today I parked the car on an incline with the nose pointing down. No problem startingat all and kept running.

Ant ideas on this? Fuel pump, tank strainer,IP?

You have a leak on the fuel feed line from tank to injection pump.
This allows air to be sucked into the line.
A very common problem.

Note:
It helps if you add year and model to question posts.

Have a great day.

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1985 300SD
1983 300D
1984 190D
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Sorry about that - 1983 300SD. Would an air leak before the IP cause this? Wouldn't the amount of fuel in the filter be enough to keep the engine running for more than 6 seconds? Does air get in that fast?

If the line from the filter to the IP has a bad O ring or crack that would be about right.
I would need to see the car to guess further.

Thank you I will check this weekend. After all what are three day weekends for besides fixing our cars.