2001 Jeep Grand Cherokee Larado 4.0 cranking issues

My Jeep is slow to crank, but always cranks and runs great! I have had the fuel pump replaced, no change, then they replaced some other part near the fuel pump. The fuel pressures are all fine. They gave up at the shop. Seeing if anyone has a bright idea. NOW get this, if you start it immediately after shutting it off, it starts fine AND if you wait 36 hours (not 24 hours) it starts immediately.

Thoughts appreciated!

BillT