My 2006 3.0 v 6 ranger truck warbles slightly at idol. At highway speeds or under heavier tow it jumps and stutter loosing power. Then all of a sudden it might kick in at full power.

I have started with new plugs and wires. When i pulled them they were all burning nice but gaps were warn badly. now, The code key says number 3 cyl. When I pull the plug wires at the coil pack, according to the book, my number6 is getting a weak spark.

Do you think this is a clogged injector or possibly a valve recession?