Since you DIY, I assume that you

know what you did. Did you use OEM spark plugs? I think Toyota uses Denso Iridium spark plugs. Did you check compability? Did you apply dielectric grease between coil packs and spark plugs? Also, make sure to apply antiseize lubricant to spark plugs when you install them. If spark plugs seize, they could cost you thousand dollars.

I had a connection issue with cylinder #6. So, I swapped coil packs between #4 and #6. The issue went away. I don't know why. I have a feeling it was a connectionn issue. For your information, my SUV is 2011 Toyota Highlander V6.

Good luck and Happy Thanksgiving!

Alex