2004 f150 5.4 3v

Okay I just replaced front cats with MagnaFlow and delegated my rear but don’t think this has anything to do with my problem just wanted to throw that out there.

I started my truck for the first time since I started rebuilding it about 9 months ago and it’s missing and I have p0356. When I unplug the coil it makes no difference but a couple times when pressing hard on the plug it started running worse almost died. When I look at my o2 bank 2 which is the same a cylinder 6 is staying below .45mv but the rear o2 is staying around .85mv. Now the driver side o2 read normal so I know it’s not the new cats making the rear o2 read rich.

The only thing I can Think of doing this is either an injector or exhaust leak which would make since with the misfire and lean o2 reads but I’ve always had problem with 6 since I built this motor. I rebuilt it about 4 yrs ago and added a supercharger at the same time and haven’t been able to feel whAt the charger changed bc it’s just never ran right. I about a 1 1/2 years ago started getting a ping at high rpm or under load at low rpm but I think the low rpm was bc my trans wasn’t downshifting and I think I got lined out recently when I rebuilt my trans myself but won’t know for sure until I take care of this misfire. If anyone can think of anything my ears are open? Thanks

I had an extra coil laying around that I swapped in. I’ve never done a compression test. But the motor has less than 20,000 and been well taken care of so I don’t think it’s compression. I’m leaning more towards injector bc of the lean reading from o2. It just hit me These o2 sat in the garage floating around and kicked around for 9 months so i could be very well screwed one up.

Thanks guys for the help but I fixed it earlier tonight. And after thinking about it today the one thing I was thinking it was,the injector bc o2 was reading lean,well it was reading lean bc of that unburnt o2 was going passed sensor and creating a false lean. Anyways it wasn’t the number 6 cylinder after all,it was 7 and ended up being the coil electrical connector. This is what I hate about ford misfire diagnostics,you cant Trust the number cylinder the code is for. This isn’t the first time,I actually had a misfire code for 8 that ended up being 4 and this thing is hard to throw a code but others are spot on.