Unstable idling

[yutopok]

Hello from Japan.
I have a 2006 6 speed manual model.
As the title says, the idling is unstable, but I don't know the cause.
What is especially bad is when I put it in reverse gear and back up, it idles like it is going to stall with a thud.
It stabilizes after a few dozen seconds. (Still not perfect stability, though.)
Also, when turning through an intersection, I have actually stalled the car when I turn the steering wheel all the way around.
I have replaced the crankshaft sensor and camshaft sensor before because of the P0340 and P0344 error codes, but there is no improvement.
I am thinking that the alternator may be malfunctioning, but are there any other possible causes?

 

[MikeE024]

Have u cleaned your idler air control valve? It’s in the rear of the throttle body next to the tps sensor.

 

[yutopok]

I'll give it a try.
Thank you for your valuable information.

 

[Mike_H]

Check your battery. I had a rough idle, Surging and very unstead with regard to RPM. Found out my battery was bad. Replaced that and its running great again.

 

[yutopok]

Check your battery. I had a rough idle, Surging and very unstead with regard to RPM. Found out my battery was bad. Replaced that and its running great again.

Thanks for your answer.
Do you have other ideas？

 

[Mike_H]

Idle air control, throttle position sensor, clockspring...

Did you check the battery? what was the result? Did you clean the throttle body and Idle air controller?

 

[AndyG]

Look on the intake there are two rubber L-shaped fittings that pull vacuum on the system-

Most of them are cracked at this age and will cause that to happen