I am the "Original" owner of my 1987 XLT 4X4 'Midnight Blue' supercab. Last summer.08, it started running rough,( 4 or 5 cylinders) loss of power, hesitation, bad fuel mileage) and stalling while letting the clutch out. I started with the no-brainer stuff; (K&N)air-cleaner, plugs,(wires are...