I also have the 03 2.3 2sd 5 speed ranger, and in my opinion it is the best due to the dual over head cams removing the lifters and push rods... meaning less moving parts. just did my 199k mi oil change and went to replace the spark plugs noticing that cylinder 3 has oil covering the plug, i have heard both reasons (cylinder, and valve cover gasket) but my main concern is the O2 sensor in the back catalytic converter aka the catalist manifold sensor. is there any way to bypass this sensor and remove the cat? if you can please help that would be great... thank you