Changing plugs can make a big difference.
 

My situation may be a bit extreme, but I am still quite surprised by the results.

My 2000 Tundra has well over 200k miles on it and was starting to stumble a bit on the occasional acceleration request. I decided to change the plugs and what a difference it made.

First the plugs may have been original, I'm not sure but they were eroded to a .090" gap! The new ones are set at .044". The plugs looked good except for the gap erosion.

Anyway, the truck runs smooth as silk again and I'm getting MUCH better mileage. I'm not a mileage watcher normally, but I know how many miles I get to a tank and I'm already there with a 1/4 tank left. Granted the last quarter on the gauge is probably much less than that in reality but I bet I'm going to get 40-60 more miles from the tank total which is impressive.

So if any of you guys are rolling high mileage war wagons like I am, change them plugs. This ends today's PSA sponsored by the Daddy:D

New plugs are great.

How did you pull the wires?

You might want to change those next, they sometimes get damaged pulling on and off and it may take a little time for it to show up.

The Tundra has individual coils for each plug, there is no conventional "plug wire".