I would take the head back to the machine shop that shaved it and have them pressure test it they should be capable of doing this. I would also inspect the cylinders very well rotate the engine and check each cylinder for gaulding and wear. The slow response and knock could most definitly be caused by a fuel injector. (fuel knock). When the oil cooler fails you generally see oil in the coolant befor you see coolant in the oil due to oil pressure is higher than cooling system pressure. Something else you may want to check is make sure the freeze plugs arent damaged that are under the rocker cover coolant can enter the oil system here. Hope some of that helps.