I have a '97 F150 4.6L with 169k miles on it. Last week, the truck started sputtering for random amounts of time, then it started happening all the time. I pulled the codes. One was P0305, misfire in cylinder #5, and (i forgot the number) system running lean in bank 2. I've replaced all o2 sensors, plugs, and plug wires within the last 20k miles, so I was thinking it was the coil packs, since they are original. In further troubleshooting, I pulled spark plug #5 and spark plug #1 (I chose #1 since it was easy to get to). Spark plug #5 was in great shape. Spark plug #1 had some carbon build up and oil all over the threads (and all over my socket). I cleaned off the plugs and reinstalled them (#5 in #1 and vice versa). Things seem to be back to normal. No more CEL. I'm really baffled at this point. Since I heard so many bad things about them, I'll be swapping out the Bosch Platinum +4's for good ol' OEM Motorcraft plugs. I'll be marking the plugs individually and they're condition/description. Any ideas? Thanks in advance!

 

Sometimes those Jiffy lube places get oil all over your engine and down into your plugs.

I've been very happy with the Bosch Platinum plugs. Far better performance than the OEM plugs. Plus, they don't corrode like the OEM plugs.

 

I have a 98 F150 with 80k miles. I have the same issue. The other day the truck started sputtering.. Check and a P304 AND 174 error. Checked the MAF sensor it looked ok.. But I think I will just replace. Change all the plugs. And I am now checking the O2 sensors and the coil. Have you had any proplnes since or any feed back on your issue?