yep, it was a cracked injector cup/sleeve. i took the truck into the ford dealer this past week. they took off both value covers, removed the injectors, and pressurized the water to determine the location of the leak. cylinder #4 (2nd from front on passenger side) was leaking. in addition to new cup, all injectors were resealed (new orings, washers, and whatever else that means), new heater hoses (9 of them), new radiator hoses, new radiator cap, flush and fill raidator, drain oil and replace filter, and about $2,700 later, the truck is running again at 90,000 miles. i better get another 190k miles before i do this again.