Vintage Cars: turning off a carburated engine, throttle linkage, engine vacuum

Question
I have an old Postal Jeep ('79 DJ5), the problem that I am having is it starts up great, runs great until I turn it off...it "coughs" (engine) for a while, then finally shuts off. I have asked some local mechanics they said check the timing, well the timing is fine, timed it with a timing light. My question is, is what are some ideas that could be causing the "coughing" when I had already turned the engine off?

Answer
My smart Alick answer is that your car has the flu... LOL.  Seriously, the problem is not with the timing.  The problem is caused by the throttle plate at the bottom of the carburetor is partially open, allowing the engine vacuum to pull additional gasoline into the cylinders, where it burns and causes the problem you describe.  I suggest that you start by removing the throttle linkage from the carburetor.  This is the linkage that connects the carburetor to the gas pedal.  Then using the factory service manual, make all the carburetor adjustments in the exact sequence that is shown in the factory service manual, and don't skip any of the adjustments.  Once the carburetor is properly adjusted you will have solved your problem.  If you are not familiar with making carburetor adjustments, then I suggest a professional mechanic needs to be consulter.