I have a 98 tacoma 5 speed 3.4L limited 270K miles and the past few months at 3500 rpm stationary or in gear it sputters and backfires. Checked and cleaned plugs, cleaned MAFS, removed cat and ran it, cleaned fuel filter, new gas, cleaned throttle body, and PCV. Still running the same way. No CEL but every now and again the check engine light will come on and when I try to pull the codes it will do nothing and then i turn it off and back on then the CEL is gone. So random. And MPG went down hill I believe as well. Have been searching for ever it feels like to find a solution and have heard some people fixing it by different ways. But the cards don't seem to be in my favor on this one!

 

I had the exact same problem (wouldn't rev over 3k) when my crank sensor was going out. Didn't ever throw a code and the sensor even ohm'd out in spec. Hope you've got a buddy to swap one with. I paid $86 for mine from Oreilly's.

Also check to make sure your crank pulley is tightened down 217lb/ft. See if there's any wobble in your crank at all at idle. That'll do it too.

 

Ya I've heard multiple people say those were some of their problems. I'm just gonna keep messing with it cause now it's not really doing anymore. But I'm not driving it around either. But CEL randomly keeps coming on and off and no codes are showing up

 

Do what you want. Mine was intermittent too. Usually it would rev out fine. The most telltale symptom of crankshaft sensor/loose pulley is the CEL blinking on while it's faultering while never setting a code. Have you checked your crankshaft pulley bolt? Do you have wobble at idle? I think you would be silly to ignore my advice because it's not acting up right now. My ignorance led to a bent rod and a new motor.

edit: also eyeball your crankshaft pulley and make sure it's lined up with the other pulleys. If the crank bolt is loose it'll be further out than the rest of the pulleys.

 

Ya I'm gonna take your advice, I just meant I'm gonna keep messing with it like check all this different things out to make sure there good. I appreciate the help. I just haven't had a lot of time to mess with it and the weather has been ugly the past while. And I don't have a torque wrench right now so I'm gonna have to get one.