Slow Crank, No Start When Warm

I would do the following

1...Install some sort of method to get an accurate voltmeter on the block and starter stud, so you can measure batt V while cranking. One way is to simply get a couple of no 14 or smaller wire size eyelets with 3/8 eyes, get some scrap wire any size, 18-14, and bring out some leads from those points so you can get a meter on them

If V during cranking and hot is down to 10.5, this could be wiring/ terminal / connection/ battery issues or high starter draw.

2...Take your battery somewhere and have it load tested. If the guy comes out with a small box in one hand, go somewhere else. You want a carbon pile load tester.

3...Specs on PM starters are fairly rare as to locked rotor amps, etc, but if the above two check OK, suspect the starter and try to get it tested, or sub another, even if you have to buy a junkyard PM starter off a late Dakota/ Ram 5.2/ 5.9 magnum