Preheat the oven to 350 degrees F (175 degrees C). Season pork roast with salt and pepper, then dredge in flour; shake off excess.

Heat oil in a large skillet over medium-high heat until smoking. Add roast and sear in hot oil until browned on all sides, about 1 minute per side. Transfer roast to a large sheet of aluminum foil set on top of a baking sheet.

Stir together maple syrup, ketchup, water, and garlic. Pour 3/4 of the maple syrup sauce over pork. Fold the foil around pork and seal to form a packet.

Bake in the preheated oven until the internal temperature reaches 170 degrees F (75 degrees C), about 2 hours.

Remove from the oven and carefully open the foil packet. Turn on the broiler and broil roast for a few minutes until the sauce glazes the meat. Serve roast with remaining sauce.