Hi T4R, I am currently having an rpm surge problem on my 2003 v8 2wd runner with 206k miles, it is an intermittent issue but when it does happen the driving is affected pretty bad. First happened while driving on the freeway with cruise control on, suddenly felt like my brakes were being pumped and the car started to stutter. I pulled over popped the hood and everything looked and sounded fine but I did notice the serpentine belt stopped spinning for a split second then continued. Had no CEL and just got it towed to a shop.

- Cleaned MAF sensor
- Cleaned throttle body
- Replaced an o2 sensor that the shop diagnosed as faulty
- Battery and Alternator test good
- No CEL code at all

I recently got it back from the shop and it appeared after the cleaning and o2 replacement it was running normal again until yesterday the same problem is happening. I noticed that the exhaust pipe smells a little like sulfur on startup now after the cleaning and the car sounds louder near the 3rd cat. I am completely stumped and can't find any info on this problem so I am hoping one of the fellow members could help me out, don't know if my cat is clogged or if it is the exhaust manifold issue on the 4th gens but any ideas would be much appreciated.

2003 4runner idle surge - YouTube

Here is a video of the surge couldn’t get in in an attachment

Do you have an ODBII reader to plug in to check your long / short term fuel trims?

Could be an issue with the throttle position sensor, which is riveted to the throttle body.

No I don't but I think my buddy might have an obd that will give me the fuel trim info I will check that out thank you

Thank you ill try and test it and see if it's bad

Thanks for the info checked the fuel trims everything was good turned out to be the tps

Thank you you were right was the tps got it replaced everything is fixed, appreciate it

Thanks for the update, happy to help!