The IAC valve controls idle RPM. Have you cleaned it. YouTube has videos on this.

 

sure.

 

I cleaned it. Can it be dirty again so soon? But when I unplug the hose from purge valve solenoid to intake manifold, RPM increased significantly. I ordered idle air control valve twice and return it twice, from Walmart.

 

Unless plugging the purge valve hose to the engine the increased air will cause the idle to go up.

 

I think I have solved the problem. Today I drove to LKQ pick-U-part and got a used EGR Valve, put it back on and drove to home. Seems good!

 

Please post back with how this works out.

 

the EGR valve I bought from Amazon 2 month ago is a fake. it leaks.

 

Good job. Amazon sellers can sell fakes!

 

But this morning my car was not stable again, maybe because the cold. Afternoon driving back was pretty good, but code P0172 come back. After getting home, I checked the fuel injectors, still somewhat leaking. Life is not easy. But seems leaking is much smaller.

 

Where is this fuel leak?

The P code is just standing the mixture is rich.