Have I messed up something with the 300D?
 

Do a PM on the car, changed out the primary and secondary filter, changed the oil. Now the car will fire up in the morning and then die immediately. It needs 3-4 start again before it stays on. It does not happen when engine is warm. It used to fire up and then stays on OK before the PM. What gives?

Any ideas?

You might be losing prime overnight do to a (slight) air leak in the fuel system (since you just changed your filters). When you expect it to show this behavior (ie in the morning), check for air in the clear filter.