I recently had to replace my f23, pretty much the same thing but it was cylinder #1 that went bad. The junkyard I got my engine from said to validate the warranty I had to get a new timing belt, water pump, gaskets, seals, thermostat, new plugs, wires. the new engine runs so much better than the my old engine even before the piston rings went on cyl#1. I got a 19K engine for $500, definatly worth the money.