Hey guys it's my first post on here since I just bought an 01 z24 5 speed 2.4l to commute to work in. So far it's been great but occasionally it will stall if I'm sitting at a light in neutral or if I'm sitting with the car in gear and my foot on the clutch. Last night a coworker was in front of me so I revved the car a little bit with my foot on the clutch and once I released the idle sputtered down and stalled the car. So far I've changed the plugs, corks, air filter, and oil pressure switch since it was leaking. I plan on changing the fuel filter and checking out the idle air control valve to see if it's clogged and causing the stall. I'm certain there's no vacuum leaks. Was wondering if anyone else had this problem and found a solution?

If the stalling problem only happens after the engine warms up, then replace your coolant temperature sensor. My wife's 1996 2.4L Cavalier had that problem. It started fine and ran well until it warmed up. Then if you stopped at a stop sign, it would sound rough and stall. It was difficult to diagnose but it turned out that the coolant temperature sensor (not the thermostat) was feeding bad (too-cold) data to the car's computer. So the computer fed the engine a too-rich fuel mixture. (It's like setting the choke for a cold carbureted engine.) The rich fuel mixture is fine when the car is cold but it causes the engine to stall when the engine warmed up. A new sensor solved the problem.

Temperatures sensors are about $14 on Amazon.

If you're even slightly handy, you should be able to replace it yourself. Just unplug it & unscrew it. Diagram here.

What I've noticed lately is that it only does it when the car is cold, once its warm and goes to open loop it doesn't seem to stall but I could be wrong. Tomorrow morning I'm gonna clean the throttlebody and Idle air control valve and see if it helps any. So far I've changed the fuel filter, plugs, air filter, and corks/wireset. I checked the fuel pressure regulator and its not sucking gas into the vacuum line. fuel pressure is around 60 psi idling.

the car does seem to be running rich, during a heavy rain one day my check engine light came on for the o2 sensor but once it dried up it went away. i recorded a video of the exhaust as my brother revved it and it shot brown exhaust fumes. previous owner put a magnaflow cat back on and had someone install an o2 sensor about a foot down the exhaust manifold from the stock one. Im guessing when it came time to change the o2 sensor they couldn't get the old one out so they welded in a new bung and o2 sensor and left the old one in but disconnected. I've done endless work to my Trans Am so doing the work myself isn't an issue.

I would bet it's the idle air control valve also map sensor can cause this issue as well but it not often. The moving of o2 sensor won't cause issues it it's not to low getting condensation on it if it is should get it fixed.

thats what I've been thinking, Ill clean up the throttle body passages and the idle air control valve and check the map sensor tomorrow and see if it helps any, thanks guys