The fuel filter can, in an extreme case, cause too little fuel pressure to reach the injector rail, which can cause a lean condition. Check your spark plugs to see if any are fuel fouled, that is the easiest way to see what cyl. is misfiring. If all plugs look the same and are free of gas residue, and the porcelain is still pretty white, then you have a lean condition. From there on requires some more detective work.

 

I replaced the fuel filter over the weekend. The fuel that came out of the back of the filter was very dark so hopefully it was part of the issue. I have not been able to test it yet as I was cleaning and testing all the injectors. Here is a picture of the plugs. They are brand new and only have maybe 50 driven miles and another 40 min idle time on them.

 

They look as if they had covered millions of miles or kilometers