Car idles low, gas mileage is about 260 a tank I drive slow don't race. Car has 197k check engine light is on, got 2 codes one is for the cat.

I did a tube up at 120k

None since.

Where and what to start checking?

 

telling us what the other code is would be a start...

 

Without the codes, only guessing, clogged catalytic converter.

 

What are the codes and go from there.

 

what fuel you using

 

Hopefully he is using 93 octane.

 

You have done a tune up since 120k?

 

Fixed whatever the codes are. Then full tune-up.

 

One code is a bad cat the other one I need to find, it's two codes but my mechanic told me to change all the o2 sensors.

About the cat converter? I'm searching on rock auto and I'm seeing a front and rear cat, do I need to spend this much money on a cat?

 

just get a y-pipe and a HFC and call it day.

 

P1572 and p0430 can someone answer the cat question about the cost?

 

P0430= Catalyst system below threshold. The other code couldnt find but Here are some others that might help you.
P0157= O2 sensor circut low voltage
P0156= O2 sensor circuit
P0154= no activity
P0153=O2 sensor slow response
P0152= O2 sensor circuit high voltage
P0172= system to rich
Also you might want to clean the MAS and TBS. Check all sensors first before go spending $300 on a cat