Spark plug Champion or Denso

Stick with Champion plugs in the 4.0L inline 6. Anything else will have you chasing a “stumbling” idle.

I use champion on my 04. No issues. The more expensive ones that’s when the issues start

I use Champion in my 02. Never had any issues.

I’ve been running champion plugs for about 40k mi without issue.

Denso work quite well

The plugs EQT recommends are compatible. I’ve been running Denso 5749 plugs for over 10k without issue

i just put the densos in my '17 alltrack with a stage 1 tune and they run noticeably smoother than stock. i gapped them to 0.026" before install. it didn't seem like plugs would be that important for a stage 1 tune so i've been surprised.

They look good but if the vehicle has 83k, they were replaced before, Denso is OE on toyota and Autolite are shit plugs so no way they were in since the car was brand new.

Champion is garbage.

Champion aren't a great brand. They may have been at one point, but not any more.