Low MPGs after Spark plug change @95k miles

Okay so I think I know what the issue is but I really need to hear other peoples opinions. I used the exact plug needed for my truck, bought it from Toyota. I checked the gap and assumed it wasn’t Pre-gapped based on my manual stating it needs to be .031. They were about .027 so I decided to gap them. Then I found an Article after I happed them saying I shouldn’t gap iridium plugs or be very careful doing so. I also kind of over gapped one of them to about .034. It’s running fine as far as I can tell, however my MPGs are pretty low, about 13/14 city and 18 highway vs. 17/18 city and 20-22 highway.

One thing I noticed when I took the old plugs out they were gapped the exact same as the news ones came before I gapped them.
Should I have just left them alone?

also, I didn’t torque them because I used anti seize on them and didn’t want to over tighten them. Could it be that the plugs are over gapped and not tightened enough? I almost want to just bought new plugs again and re do it with the gap they come with.
Also attached a pic of how the old plugs looked.

 

Just what you mentioned .

 

Tighten the plugs.

 

And lay off the anti-seize. You really don't need it these days. Install, torque to spec, and drive.

 

Do you guys think I should get new ones though? I don’t think I should have gapped these, the old ones before worked fine at factory gap.
Ya I read about not using anti-seize, I’m not going to use that again.

 

I'd drive it a bit first. And I doubt tweaking gap hurt anything.

 

The iridium tips are very fine and are not recommended to gap as the gapping tool could cause damage to the tip and could cause irregular/insufficient spark patterns. If you continue to get less than usual MPGs after plugs then I’d replace them again and torque to spec. Do not over torque! As it could damage the fine wire electrode.

 

Using anti-seize is why I would want to overtighten a bit. I prefer not to use it and overtighten, anyhow.

Increasing the gap is what's hurting your mpg's. If a plug got messed up the truck would run like crap.