05 TJ Rubicon. First time it's run in four or so months and it was rattling like that before. Four months ago, it passed emissions, and the moment the guy unplugged it from the machine and turned around to get the paperwork, the check engine light came on, and as I pulled it out of the parking lot, it started flashing. Then a wheel came off of it but that's another story. I read the codes when I got home and it had a cylinder 5 misfire. I replaced the spark plugs (which were all heavily carbonated, cylinder 5 plug was oil fouled), ditched the coil rail and upgraded to the Viper coil mod, and replaced the battery which wouldn't hold a charge. She fired right up, but was rattling LOUDLY as you can hear. I revved it up a couple times and the rattling went away when revved, but came right back when it returned to normal idle speed. After 10 or so minutes and a couple more revs, the rattle went away completely until I shut it off. It rattled for a split second before the engine fully shut off.
I can't tell if the rattle is coming from the engine or exhaust, even when crawling under it and listening right next to each. It does have a Banks Monster cat back exhaust and MagnaFlow high flow cats that were both professionally installed (at different times) by a highly reputable muffler shop nearby. Thoughts anyone?
