odd stumble when accelerating

[RLC2020]

Well, I guess I spoke too soon. I didn't drive the truck for about a week, I took it out yesterday and it stumbled again after the second gear shift. I'll have to check the fuel pressure for sure. I may just bring it in somewhere as I really don't have the tools to diagnose this myself. It's either the engine loosing power, or the trans upshifts or goes into lockup, I can't tell which it is. The rpms drop and I basically have to floor it to get it to move. It's borderline dangerous, I almost got rear ended yesterday when I pulled out into traffic and it fell on it's face. Oh well. I'll update again when I have some more info.

 

[RLC2020]

So, Over the weekend I was driving the truck and it did the stumble but this time it actually lit the CEL at the same time, It had not previously thrown a code. Flashing CEL so I pulled over and by the time I stopped so did the CEL. Drove fine after that, got it home and checked the code, PO307 Cyl 7 misfire. I pulled the #7 plug and it looked like this.



I swapped the plug out for a new one and drove it about 50 miles since and no issues since then. Could it have been a bad plug this whole time? Thoughts on how that plug looks? The truck only has 56k miles on it so I shouldn't be due for plugs yet, but I replaced them anyway.

 

[Fless]

Any cracks in the porcelain, or carbon tracking there?

 

[RLC2020]

I did not notice any cracks, but I'll clean the plug up when I get home and do a better inspection of it.

 

[OR VietVet]

May not be the plug and could be a wire that will give you an intermittent problem. But, like @Fless said, could be cracked porcelain or tracking from a poor seal at wire insulation boot.