Intermittent rough idle issue S.O.S

Hey guys my names Daniel new to the forum i have an 02 tundra 4wd access cab unlimited. For the last three months ive had intermittent rough idle it happens sometimes on cold starts but it also happens frequently in drive at full stop the truck goes from 700rpm to 500rpm sometimes lower and almost stalls but has yet to stall, the truck isn't throwing any codes or misfire codes.

so far the work ive done to fix the issue is clean the throttle body, i then cleaned and regreased the fly by wire mechanism on the throttle body, cleaned then replaced MAF, replaced TPS and the other day i put in new plugs(NGK iridium IX)

I havent been able to pinpoint the issue if anyone has an idea of what it is i'd greatly appreciate it! Heres a pic of my rig and the throttle body before i cleaned it

 

I would check the fuel filter next.
Just sounds like a fuel issue.

 

Have a code reader check to see if there are any pending codes.

 

I would throw a can of Seafoam in your tank and change your fuel filter, love your black 1st gen though buddy that's one clean looking unit.

 

Harmonic balance is off?

 

1st-welcome to the forum. Love your truck. 2nd- you've done all the things I would have done. My wife's Rav4 has a similar issue and when trying to diagnose it I kept getting these suggestions- The idle air control valve or throttle position sensor. @empty_lord do you have any feedback on this issue for OP?

Edit-just re-read your post and realized you already replaced the TPS. Did you go OEM on this part?

 

With issues like this it’s best to have a scan tool capable of graphing to watch what the sensors are doing, it can be a million things. These are known for the throttle issues. So It wouldn’t surprise me if there’s a issue with it finding idle

 

Check for cracks in the intake and any vacuum hoses. Could be a slight vacuum leak.

 

If you replace the fuel filter, have someone else do it. I HATE that fuel filter.

 

Unfortunately it was out of my budget to go oem(broke college student) the dealership want $180 so I ended up picking up one from autozone for $90

 

Update changed fuel filter idle did fluctuate at start up but stayed relatively still in drive however was still low at 500rpm

On the bright side my transmission shifted 100% better with very little to no slipping although this was only after initial test drive

 

Hello.
I’m new to Tundra’s myself, but have had a T100 for about 15 years.
I had intermittent idle issues on the T100 and it was due to a plugged idle air valve (as suggested above).
I’m not very familiar with this engine yet, but with the T it could be removed and cleaned.
I was able to improve it with Seafoam intake cleaner (different than regular Seafoam), you spray it in the intake with a long tube while the truck is running, and since it’s at idle while doing it, it has to go through the idle air valve.

 

I haven’t been able to find any pics of the IAC valve and that is what my mechanic said might be the problem

 

On the T it is under the intake, not particularly accessible.

 

I had to take out the battery in my 02 a few times and after I put it back in it took a lot of cranks for it to start up. At stop lights it would die unless I pushed the accelerator and no codes thrown. I found out that if I ran it with the A/C on at idle for about 5minutes everything went away Havent taken out the battery in a couple years and no issues. Might give it a try Good luck

 

Buy a vacuum tester at one of the parts places to make sure you’re holding a steady reading. If the needle bobs around or is inconsistent it can point to a leak & other issues ( the gauge will help diagnose more than just a vac leak ) they are cheap. Or borrow one from a buddy!!!

 

When the AC on the truck will idle up to help with strain on the engine. Probably why yours won’t die at lights with the AC on.

 

Ive taken out the battery before on a tacoma and it took a few miles when reinstalled for the computer to recalibrate etc. — acted like it wanted to stall, low idle, but eventually after some bit of driving, went back to normal....

 

I forgot to mention I turned off the A/C after the 5 or so minutes you can even drive it around during that time. For some reason on my 02 it worked but it had all the same symptoms as the OP/ Ocdan

 

Well I still haven’t been able to fix the idle and recently it finally threw 2 codes a p0171 and p0174 I looked it up and it could be a couple things most likely a vacuum leak or bad o2 sensors possible a issue with fuel system if anyone has some input on what to try first let me know!

 

02 sensors. One of the most important sensors on the vehicle. (the ones before the cat, the ones after are just emissions BS)