Mercedes Benz repair: 300sd engine miss, leak fuel, valve adjustment

Question
our 300sd has a mis at idle after driving for a while

Answer
More data needed:
#1. Year, make, model, how many miles?
#2. When was last fuel filter change?
#3. Do you hear hissing or sucking sound from fuel fill cap when opening?
#4. Are any fuel lines damp = leaking?
#5. When was last valve adjustment?
#6. Are you running pure diesel or a vegetable blend?
#7. What was the last service done to vehicle?
#8. What is your zero to sixty miles per hours time?
#9. Does your fuel primer pump leak fuel when used?