dml996- you may have just gotten a crappy set of cops like i did. the first set i got from amazon were the eccpp brand ($30 for a set of 8) and they didn't last one day of average driving for me. i think i put on like 80 miles or so that day. mostly stop and go city driving and they failed horribly. by 4pm they were misfiring like crazy. all random. they were misfiring worse than the ones i was replacing. to get a better idea whether or not its your cops or engine that has the issue, swap cops from a cylinder that has no issue with one that has it. erase codes. if the problem switches to the cylinder you knew had no issue, then you know its the cops. if it doesn't. then its either a bad spark plug/ bad connection/cylinder itself. are your plugs new? fully seated? i read this engine has a habit of kicking plugs out. also while online i notice a lot of sellers selling new connectors for the cops. the way the engine is designed with the plate covering cops and connectors, i can see them failing in time with all that extra heat building up in there. crappy design in my opinion. well here's an update on the new cops i put in. these are the parts galaxy brand on amazon. $40 for a set of 8. i installed the new cops last sunday. now since then the temps have dropped and i haven't driven as much as i usually do but ive put on 100-150 miles this week running the new cops and so far, no more misfire. because they're new, i run the engine harder than i normally would to see if i get a failure. hard acceleration from stops etc. i still have a check engine code but its still 02 sensors and my gas mileage is still lower than it should be. i have catalytic converter rattle and with the way it was running when i first got it, wouldn't be surprised if the cats and muffler are gone. all that aside, since i put in the new cops, accelleration is smooth, responsive. strong off the line and passing at highway speeds. smooth idle. quiet engine. so far so good. i got 90 days to swap them out if something fails. im hoping for some warmer weather to see if these things hold up to the heat. i figure even at 90 days, if i have to swap them, then its $40 for all 8 as opposed to $320 for a set of motorcraft, i'm cool with it. $40 bucks is like a crap dinner at tgif without drinks. ill pop in some new 02 sensors and start fiddling with the abs sensors to see if one is out or if its just the main module acting screwey. i have the same issue on my mustang. repairs done- tune up- $25 Replace valve cover gasket/tube seals-$26. (valve gasket was fine. tube seals were leaking) oil change- $26. replace valve stems on 2 tires - $30 total. so far so good. For a fully loaded truck with all the bells and whistles that cost me $906, im not complaining.