My 4runner is 4wheel drive with a 3.0 engine. I noticed it wouldnt start up the first when it was around 50degrees or lower, poor gas mileage, also everytime i would stop it would die on me so i would press on both brake and gas pedal at the same time, so i did some research and replace a few things. Here is the order:
Throttle position sensor (it fixed part of problem)
Fuel pressure regulator (im thinking it could be defective because you can hear a sound coming from it, like if it was struggling to pass fuel)
Fuel filter (it really didn't improve anything)
Now this past few days the colder it gets the longer it takes to start. Also after driving it for about 20-30 miles it will hesitate to get up to 60 mph so i loosen the gas tank cap and you can hear pressure being released, its like a hissing sound and you can hear it for about 5seconds. I dont think that is normal.
Also, the fuel economy improved just a bit