Vintage Cars: 1979 450 sl, fuel starvation, vacuum leak

Question
my 79 450sl starts up on the first try , but when it shuts off its hard to restart and usually won't until a long time passes.

Answer
Ken
I have to know a lot more than what you gave me to help :)

Is this a sudden occurance?
How many miles?
Last service and service history?
Any smoke?  Color?
Cold starts always good?
Hot starts always bad?
Smell fuel?

to start, we can go form there. Usually hot starts issues are related to compression , fuel starvation, vacuum leak or leaking injectors, but there is a host of other possibilities
Ron