3.4l prerunner engine surges at medium throttle

my 99 prerunner surges at mid throttle. easing along its smooth and easy and wide open throttle it shits and gets but mid throttle it surges you can feel it and hear it. It still shifts smooth even tho its surging. any help btw its completely bone stock with 339,000 miles and still runs strong.

 

Start by cleaning the MAF sensor-bet it can use it and congratulations to your tough truck for giving all that service!!

 

absolutely no codes have popped up its just aggravating ill have to look up how to clean it

 

They have MAF cleaner at the auto stores-very rapid drying which is what you need. I assume your airbox is the same as my 2001? Can you tell us or do a pic of the airbox and sensor location should be right behind it. If it is the same I will tell you how to do it. I do mine every 5000 miles. If I can I'll try to do a vid if you need one let me know.

 

mine is right after the airbox the same as my wifes 2000 4 runner. i work on helos so ill probly uses cpc type II its cleaner fast drying and all of that.