Fix vapor lock

SOURCE: 1997 buick le sabre

its the electrical connection at he fuel pump,if this is ok ask if they replaced the strainer on your fuel pump,your fuel pump is inside your gas tank ,you have to drop the tank to service,most fuel pumps are not warrantied if you dont change the strainer,when your car shuts off the sediment on the strainer falls back into the tank,but when you run your car and it sucks up the gas thru the strainer to the pump it clogs the strainer and the fuel pump cant pump,you shoiuld find out if they changed this because your forcing your fuel pump to work harder,was it a new fuel tank or used one that they put in

SOURCE: idling and running problems, engine stalls when started, backfires thru carb

timing chain/belt ?

SOURCE: fuel filter

too much air likely... find the vacuum leak

SOURCE: 1986 Ford Bronco dies once it is put into gear

Sounds like a fuel mixture/vacuum problem. Vacuum advance line on the distributor could be loose/leaking/collapsed.

SOURCE: Engine dies for no apparent reason after several hours running

Sonds like a sensor putting out an error code to shut it down ( like a fatal error code) Prolonged vibrations and heat can make cam sensors, maf, o2 senosr do craz ythings which will actuate a govener and stall your car...could also be you fuel pump causually telling you that "hey im bout to die".I dealership can run a stress test (if you will) to check the longivity of the pump...
Good luck hope this helps :)