Over the past few months I've noticed a drop in gas mileage on my 1996
4Runner. I keep maintenance up to date....check tire pressure every 2 weeks, recently replaced the plugs (with denso from the dealer), and rotate the tires every 10k. The truck runs fine but my gas mileage seems to be off. The truck is a 4x4 with 3.4L V6 and manual transmission. Mileage has dropped from 19mpg to 17mpg with mostly highway driving....
Any suggestions as to where I should start to look to fix this problem
Truck has 93k miles on it.......