Ok so Ive got an 04 ranger edge 3.0l with a 5 speed manual. It started actin funny yesterday mornin, especially in the lower rpms and it threw a cel. I took it to autozone to see what code it was showin and the guy there said it was misfiring in the 3rd cylinder around 1000 rpms. What would cause it to do this, especially in only the lower rpm range? It stops doin it around 1500-1600 rpms.