You might want to try pouring a couple of buckets of cold water over the injection pump when the car is hot. Sometimes injection pumps are well worn.

Also try to get some voltage to the glow plugs or check to see if there is any there for a little time before the engine is turned over. The occasional diesel that runs well in general etc. Just does not like to restart hot without some glow plug participation. Had a volkswagon diesel engine that was not interested in starting hot without some glow plug activity. Never knew what it was as that engine started well at even very cold temperatures otherwise. So it was not unreasonable the compression was decent.