Fuel injectors on Powerstrokes require good oil pressure to fire the injectors. It may be getting low oil pressure. Is the oil in the unit diluted with diesel? May be simple to fix with fresh oil or as I have had customers in the past use block heater to help enough with start up friction so it spins faster.

I have also replaced all the battery cables to allow for better transfer of power to spin the starter and supply adequate voltage to the rest of the system.

Thanks for the fast reply. Fresh oil, fuel bowl cleaned, does improve with faster spin by attaching more batts in parallel. Scan tool shows 4,000 kpa pressure.  Trying to find a DC clamp meter that will reach down in there for glow plug load

Use an IR temp gun and check temps around glow plug(s) with engine cold glow plugs on.  An easy great indicator of it heating up.  I'd do a warming blanket on it too as mentioned above.  Now, the issue, I would suspect due to it formerly being an ambulance, you have low compression on all cylinders thus causing the diesel hard to start issue until metal expansion causes a bit better compression.

Those are great suggestions. Being a econoline van vs a Pickup you can only fit a Twizzler in there. My Amprobe wont fit to see to check glow plug draw. A remote DC clamp to read is required, searching now to find and will report findings. Compression would like to check, hard to do. At 164k not as likely to be low as when 250k miles.