Hello Everyone,

Would like your input on a problem I have been having with my 04 Mazda3 2.3L Auto.

- CEL is on.
- At a dead stop while in drive my RPMs will dip very low around 500rpm and then bounce up a bit more and back down.
- Lastly when I start of from a stop while in first gear the engine stuggles to move the car...at around 3000 rpm the power returns and the car accelerates as it should. It is almost like taking off from second gear from a dead stop (just feels like that)

I have had a mechanic who I don't fully trust check the CEL and he said it was my O2 sensor.

Just wanted everyones input on this.

The other weird thing is the CEL went off for the past 4-5 months and there were no issues with the car and just yesterday the CEL came back with the above problems.

Any help is appreciated.