I have a 2005 sienna le 3.3l v6 , with 336,000 km's. I replaced all 6 ignition coils and iridium plugs, due to the misfires as noted from the codes. I took the van in to get the codes reads and he told me it was likely all the coils as he could see alot of them were cracked at the bolt hole. I put Delco coils and Bosch plugs in myself. I put about 3k more km's on the van with no misfires untill the misfires returned. I suppose a coil could be at fault again but I would need to get the exact fault read again at the dealer (another $135). I added STP injector cleaner recently with no improvement so far. Should I consider replacing the injectors as todate I have not done any service on them?