1998 4 runner 3.4l motor
new parts

Rebuilt motor (prem parts)
new fuel pump
New filter
Changed maf to later model
Plugs/wires
Coil packs

It idles decent maybe a touch rough and it has plenty of power but when I hit the gas it cuts out just for a split second and goes fine the rest of the gears. Like a vuh-ut-roooom haha! I do have a running lean code but I associate that with the new maf, or the crap temporary exhaust I whipped up just so I could get the 02 sensors in (stick welded 😂😂😂&#128514 maybe this is the issue?? Thanks guys

 

Get your lean code fixed .

The NEW Style MAF or Exhaust will not give you a lean code .

Maybe a PO420 if you have leaky exhaust.

Sucking Air anyplace you should not be ??

Your sure more codes have no tripped??

 

So after 2 days and one screw it turned out to be the aftermarket air filter I had on, it was too restrictive. That's what I get for going cheap 😂 my word I feel stupid, thanks for the help man!!

 

Mine doing the same thing and it's annoying as heck, especially when I back off the throttle a bit and reapply the throttle....it has a slight hesitation and I think that's also causing a downshift of the tranny. Does just fine when accelerating and when cruising with pedal in a fixed position. I took a crappy aftermarket MAF sensor out someone had put in and installed a new OEM MAF, seemed to help a lot but not 100%

I'll try the air filter, it's probably due for one anyways...thanks for posting your fix!

 

Guys,
Please others in the future by telling us which after-market filter you've had problems with so we can avoid them, too. That's what this forum is for; To help people solve their problems and to help others prevent problems.

It could also be bad fuel leading to clogged injectors.
It happened to my Sentra in 1986 - solved with STP fuel injector cleaner.
It also recently happened to my 1986 truck upon leaving the back roads of Utah. Hesitation when accelerating. A few tankfuls of fuel from better sources combined with 2 treatments with FI cleaner and it's fixed.

 

Twas a short Spectre one 😅😅 I just had it laying around haha!