Warm stall problem

In need of troubleshooting help. I have problem with an occasional stall that occurs when the engine is warm and slowing to a stop. I have a 1994 fuel injected E-350 460ci motor home. The engine runs great 90% of the time. When cold or sitting the vehicle will start and idle great. After warming up 5-100 miles occasionally I will slow down to stop, the rmps will fluctuate from 400 to 750 rpm as will the vacuum then die. The engine will start up fine but idle roughly wanting to die again during this period. Once the rpms are above 1000 and put into gear the engine will take off and accelerate great. This stalling tendency will last about 15 minutes (if I stop) then appear to go away and not reoccur during that trip. At high speed and hill climbing the engine does great. It has occurred once on each of my last 4 trips.
I have had suggestions about: the fuel pump, fuel pressure regulator, and possibly the crank sensor. I’m trying to figure the best sequence on working this problem up. It might be tough in that the problem seems to go away after about 15 minutes regardless if the engine sits or is run.
A few more notes: the rpm and vacuum are great and steady until the problem kicks in. Last summer a shop replaced: the computer, alternator, spark plugs, egr valve, and fuel filter. I think the parts were just replaced till the problem resolved. The problem (unrelated) seemed to be resolved after the work was done though.
Any suggestions would be greatly appreciated

I have almost exactly the same problem with my 97 Explorer V6. I can’t wait to hear what the answer might be. I was thinking fuel pump but like you never have problems when demanding a lot of fuel like climbing hills or accelerating.