As title says, my car has been stalling whenever it's shifted into neutral or park. Sometimes it won't fully stall but RPMs will drop low, then up a bit higher than typical idle a couple times before settling at the normal idle. I can prevent this by just giving the gas pedal a little tap after shifting to either of these gears.

​​​​​​This started after I was working on it and had removed throttle body/egr valve to clean both. Seems to me to be an issue with most likely the idle air control valve, but perhaps could be throttle position sensor, but I am inclined to say IACV as aside from in park/neutral, the engine seems to function properly.

Should also note that when driving after about 5 minutes of driving, the car goes into "failsafe engine mode," which typically seems to correlate with me letting off the accelerator but I can't say conclusively whether that's the only time it happens. No CEL, my current theory is that when I cleaned my IACV I let some of the deposits drip into the IACV. Going to do some more diagnostics and attempt to fix it tomorrow (spray a bunch of throttle body cleaner into the IACV), but I hadn't seen any threads about this particular issue so I figured that I would make one to document the process for others as well as to see if any of you may have some advice that would help guide through the process, or indicate other potential causes.

 

I should also add that cruise control has been non-operational since this began.

 

Haha another thing to add, I initially disassembled to clean the EGR valve to fix a CEL caused by the EGR valve being completely blocked up, got rid of most of it but still some left. Might be caused by this? Haven't had a CEL since though.

 

Maybe take a look at the underside of the bellows on your intake. That’s a very common failure point as the exhaust manifold will cook the thin plastic bellows. Also, follow the cruise control vacuum canister on the TB to the vacuum reservoir located underneath the air filter box. Make sure all those lines are not leaking vacuum and aren’t kinked.

 

Have a look at the fuel trims before you shift and as you do.

The before ones may show a leak.

As it stalls there may be time to see data or may not.