Fuel Economy Help?

So i just recently bought a 99 Tacoma 2.7L 4x4. It has a 3inch lift on it and 33inch tires. The first fill up i got okay fuel economy probably 15-20mpg, but i just filled up my truck, and I've gotten terrible fuel economy! I've gone 68 miles and my truck is at the 1/4 fuel mark. It has 129,000 miles on it. It's a California truck that was brung up to Canada. The weather has been really cold here around -30 degress Celsius. I haven't been driving around in 4x4 either. The truck doesn't misfire, it runs fairly smooth, however today i was having a hard time keeping 60mph, i had to keep downshifting into third speeding up and having it floored in 4th and it wasn't keeping the speed limit.

What are known issues and things i should replace first?

Here's a picture of my new Taco.

 

hmm.. you could try seafoaming, i did my 2002 2.7L with 140,000 miles. it definetly helped and it seemed the engine ran ALOT smoother at higher speeds and acceleration
give it a try and it it continues maybe have someone take a look at it.

 

I can do the work myself on the truck, i just finished replacing my slave cylinder on my old ranger, (you have to pull the tranny to change it, good engineering!) I was just wondering about common issues, related to maintenance items.

 

I would try the basics..

To save money inspect everything first..
1. Spark plugs. See how they look.
2.Air intake see if it is clean and free of debree
3. Check the tires PSI.. but this is part of the issue.
Get skinnyer tires or light wheel and tire combo...
4. add the Deck Plate mod
5. Seafoam, but change SPark plugs after words for sure then.
6. Do a Oil Flush with ATF fluid...
7. change fuel filter. this is not fun
8. check for leaks inthe Vacumm system on the intake side
9. make sure the 02 works
10. disconnect the battery for 15 mins, and let the truck reprogram it self.
this is what I do.. i think ithelps, but I have no proof...
11. replace all fluid with synthetic fluids like Redline or Mobel 1

well try this list....

 

Excellent list! Thank you.

I will check my spark plugs today, and will replace them even if they look okay.
I just changed my air filter 2 weeks ago to a K&N so it should be alright.
Tire pressure is 35psi on all 4.
First mod i'll do is the deck plate mod, i already looked it up.
I got an oil flush already done, and i am running synthetic in the front diff, rear diff, transfer case, engine, and tranny. Expensive but i love my truck.
I will look into the fuel filter..
I did replace my battery last week... Maybe the truck is just getting adjusted to the atmosphere here?