Message: I have a 1999 3.9L 4X4 with 116,000KM. There is a quite knock in the engine. The other day I started it up and there was a loud knock in the engine. The loud knock went away after a minute and I haven't hurd the loud knock since just the quite knock that has always been there. What could this be gas, plugs, wires etc. Any help will be apreciated.