Thanks to you all for the ideas! Since driving is not an

Since driving the car is not an issue, I will make the easy tries first.  I already bought an O2 sensor but fearing it may not do anything and the trouble of getting under the car to replace it.  I will try the cleanings first and see what happens, and start from there and then the more difficult ones if not working.

I will update my result.  Very appreciate all the suggestions and ideas!