I have a 2000 4x4 AT 3.0 L V-6 that will not turn more than 3700 RPMs, with the peddle to the floor 4000 RPMs is its max and is running very rough. I have changed everything I could think of. Plugs, wires, coil, EGR valve, EGR sensor, and camshaft position sensor. I have 67 PSI fuel pressure...