I am having some issues with my 94 Land Cruiser. First off, the rubber hose that comes off the block on the drivers side busted and was leaking coolant. That has been fixed and there is no longer any coolant dripping. I got that issue fixed in the A.M. and then drove around for about 20+ minutes and then proceeded to go to work. The truck operated normally. I get back in the truck about 4 hours later and I notice that there is now a noticeable stutter in the engine. This stutter occurs all the time. During acceleration, deceleration, idling, etc. there is a very noticeable stutter that shakes the truck. I had an CEL so I pulled the code and it was a 28 (second o2 sensor). I have had this CEL for some time and did not pay it any mind because the truck was operating normally. Since the stutter started I have replaced the spark plugs. I noticed that on the third cylinder the spark plug was wet with gas and that the plug was pretty fouled. I have done some research on these forums and I have figured out that it might be the pre-filter located in the gas tank. Would this be a logical next step for me? Any and all help is very appreciated.