Resently we bought a 2000 Tacoma Prerunner 3.4 V6 and it is getting 15mpg. We have changed the air filter, fuel filter, and checked the catylytic converter and cant figure out why it is getting such bad gas mileage. I was wondering if anyone give me some ideas on this or if it just get 15mpg.

What kind of driving are you doing? Do you have an aftermarket air filter? Have you changed the air filter? What's your mileage? Have you tried to clean the MAF sensor yet?

I do normal driving, mainly on the highway. No I have not checked the maf sensor. What gas mileage do you get because based on what I see on here your truck is the same as mine.

I get about 18 or 19 with mainly highway driving. With mainly street driving I get about 16. You haven't answered my other questions, more info needed to help. Below is a DIY on cleaning your MAF and throttle body. Use MAF cleaner (can be purchased at any auto parts store) and don't use a Q-Tip to clean it, it could be a costly mistake.

http://4runners.org/writeups/throttle/index.html

It has a stock air filter and I changed it out. It has about 190000 miles on it.

Clean the MAF and see what results you get.