I have a 2006 Lancer RA and the RPMs are fluctuating. Idles around 1500-2000 RPMs and will dip down to 500 or less sometimes stalling it out. Sometimes the Throttle doesn’t work either and the car smells like straight gas. What could be causing these issues? I ran the codes and the following codes are what pop up.

p0420
p2100

ive replaced the Throttle Actuator Sensor Module. Also car is straight piped and does not have a CC on it but the O2 sensor for the exhaust pipe is still there.

Can anyone please help me out?

 

Mines a 04 jus started boggin down to 500 rpms only when I come to a stop tho. No codes or check light or smell

 

I was having bad idle issues from two separate problems.

Low idle and sometimes stalling out, especially in wet weather for some reason, was solved by cleaning the throttle body. It took an ECU reset and about 15 minutes of learning to figure out how to idle again but it was worth it. There was enough carbon buildup to nearly cut off airflow when the valve was closed.

I had an issue with the revs getting higher and higher in hot weather, and/or stop and go traffic. Turns out that the throttle cable that ran to the front of the engine bay has a coil of metal as a sheath. This came slightly apart in one section and when it would heat up since it was no longer one solid sheath but now a coil, it would expand and pull on the throttle cable. More revs made more heat compounding the problem. Stop and go traffic didn't have enough airflow under the hood to help this. Replaced the throttle cable and ran great after that.

 

Check your throttle cable and clean/replace your mass air flow sensor.