Just wanted to post here to give a big shout out to @baseballfanz
for posting the cylinder order. My truck started running really rough and the Service Engine Soon light started flashing while towing my trail trailer this weekend. I already found a similar post about how to throw the truck into diagnostic mode via gas pedal presses etc. and was able to determine which cylinder was causing the misfire, but wasn't sure which one it was on the block. Because of this post was able to go buy a new coil and replace the one throwing the mis-fire error code, and that fixed the issue. I also went ahead and replaced all the spark plugs while I was at it to rule that out as well. Good thing too, because based on how bad the old spark plugs looked when I pulled them out, i don't think they had ever been replaced on the truck (almost 16 years old)! I do know that it was the coil that was the issue though as I replaced all the spark plugs first, then drove it a bit and realized it was still misfiring on cylinder #4, so came back to the house and popped on the new coil($63 from O'Rileys) and VOILA, That was the fix!!!
Thanks again for this post and ALL the other posts on this site... you guys (and gals) have provided a wealth of knowledge on so many of my fixes over the past 2 years Hopefully I will be able to contribute to this community more in the future as I do more updates & repairs to my 2004 first gen XE Crew Cab.