I have a 94 4Runner with the 3.0L.

On warmup the engine surges at idle and if I rev up to 3000rpm it drops 800rpm and runs rough.
Looking at the Haynes manual for checking the air valve it says when the engine is cold the rpm should drop when the idle adjustment screw is turned closed. If the engine is warm the rpm should not change when the idle adjustment screw is closed.

The rpm drops on my engine when its warm - it drops so much it dies.

Where is the air valve on the V6? Is it part of the throttle body? Is there an air valve on the V6?

The illustrations in the Haynes manual only shows the 22RE air valve.

Throttle position sensor

details details

The truck hasn't been running right for a while.

Started with a surging idle when the engine was warming up. The idle would jump 200 - 800 rpm - not all the time, but occasionally.

Engine started running rough on warmup. I could hold the rpm at 3000 and watch the engine drop on its own to 2200 rpm and act like it was missing.

Driving while the engine was warming up OR during cold weather the truck would start bucking like the engine was missing.

Gas mileage went way down - exhaust smelled rich.

Kept getting error code 25.

Replaced the fuel filter - helped, didn't fix.

Replaced PCV - didn't fix

Cleaned the EGR - caked with residue inside the manifold, but valve itself was still fairly clean. Helped but didn't fix.

Replaced Fuel Pressure Regulator - Needed to be replaced and definitely made things better, but STILL didn't fix.

Cleaned throttle body - helped but didn't fix.

Read somewhere that the Throttle Position Sensor is the cause of many troubles that would not be logically associated with the problem. Occured to me that it was indeed the sensor sending faulty data to the computer, thus the surging, bad gas mileage, rich mixture.

Replaced the Throttle Position Sensor - fixed, BUT kept getting error code 25.

Ran some real nice petroleum based injector/fuel system cleaner through tank - engine purrs like a kitten.

Bought the truck used and have never had it run so nice.

Hope this helps.

Thanks. will help us 2nd gen guys in the future if we run into the same problem.

I am going through pretty much the samething. I just replaced the o2 sensor. During this episode did the check engine light come on? Mine is on after about 3 minutes of start-up and stays on all the time.
Bob

Just to update, my EGR is sticking intermittently on warmup, so I have a little rough running for a few seconds. I'll take it off and run some good cleaner through it with a nice rough steel pipe cleaner. After that I shouldn't have any work left on the truck - apart from the front drive shaft and brake calipers I replaced this weekend... oh, and the faulty back door switch. I'm starting to 2nd guess why I sold my '88 22RE to get this 4Runner.

My engine check light comes on intermittently because of the sticking EGR (I believe). I get 25 for the error code which is short for Lean Malfunction.

Have you found the error code for the engine check light?

Hey guys, i have a similar issue but mine happens intermittently. It seems to happen when i run the truck for a bit, say around the block a few times or maybe a trip to the store. Then i shut down and try to start up again. It starts, idles really low and rough, and makes kind of a knocking noise. the engine shakes like it is not getting enough fuel or oxygen. So far i have tried cleaning the throttle body, the mass airflow sensor, all the tubing, i had it checked for vacuum leaks but there were none according to the mechanic. anything else it could be? I am a novice mechanic and i am at my wits end. thanks in advanced.

Did you ever solve your issue with the rough starts? I am have the same exact problems & so far fuel regulator, injectors & MAF have not fixed my issue.

New rebuild, sensors, injectors, full tune up parts, wire harness connectors, new ECU, etc.

did you find anything.

Did you resolve your issue?