Running a bit rough

Hi everyone. My 1997 4 cyl tacoma stock except k&n air filter w/ 206k miles has been running a little rough for the past year. Basically it falls on its face every now and then at >10% throttle. It does this warmed up or cold. Ill be cruising, using barely using any throttle, and the engine will completely cut out for half a second before resuming normal power. It only does this at low throttle. The Air intake temp reads about 20 degrees higher than ambient temp w/ the engine cold. The throttle position sensor reads 12% at idle. Does this sound off? I should add that the valves haven't been checked to my knowledge. It also sounds like there is an exhaust leak from under the hood. Not a ticking sound from the headers leaking, but the sound you would expect to hear from a hole somewhere down the exhaust pipe.

Any input is greatly appreciated!

 

My only experience with a temperament engine like this was an electrical issue. Just bad wiring. A wrong bump would cause it to shut off for a moment.

 

Are there any codes coming up? Try swapping coils and spark plugs.

You might have to clean your MAF, K&N filters tend to gunk up our MAF sensors. I threw mine away and started using regular paper filters.

 

I just got a code today. P0120 Throttle position sensor. I read that gunky throttle bodies can cause this code. The rough running condition started a while after my ERG valve failed, which causes a rich running condition. This might explain it. My next step ill clean the tp's and if no improvement, replace the tps. I will post what happens. Thanks!

 

FYI, my TPS is at 11% with ignition on, not running.
Then, when running a idle, it shows 9.8%, hot or cold.

I use an Ultragauge to monitor it.

Definitely clean the MAF (and air intake temp sensor) with MAF cleaner (NOT tb or carb cleaner).

 

Good to know. Thanks.

 

To check for a vacuum leak you can use a small spray bottle with water and just check those areas looking for bubbles. I use to do this, just find the vacuum points for your engine.

 

The bubbles won't show on VACUUM line leaks, it works only on PRESSURE line leaks