Rrmorris67

Hi there. Regarding my 2010 Mazda 3 with a 2.0 it has 200,000 miles and had a hard life before I got it a few years ago.

Starts and runs real good, but Lately it began to throw these engine codes: P0171 and P0300.

It has a choppy idle, but when I get on the gas the power under load feels strong and smooth like normal.

The MAF sensor is pretty new and is clean but sprayed it with maf cleaner, anyway. The spark plugs are newer. I just replaced all 4 coils hoping it would help but it did not.

any ideas? My theory right now is that I've got a vacuum leak somewhere since it is rough at idle but smooth under load.

Could it be one or both of the exhaust sensors? The one near the manifold and the one on the cat?

I've looked around and there's no obvious vacuum leak I can find.

Anybody have a similar experience? Would appreciate any input. Any ideas or similar experiences. Where I can look, next.

Thanks

Rob