OK. Got it. One could access it from the top after removing air intake tube.
So I did replace the O2 (Bank 1 Sensor 1) but the car still has rough idle and shakes even more when I turn the AC on.
I did scan for code and I am getting P0173, P0170, and P0130 (pending). The scanner does not clear the codes and it kept saying: Command sent 3 codes remain.
Before changing the O2 I did:
clean MAF (no go)
Replaced the MAF insert (no go)
Note: I bought the MAF insert from ebay which I think is generic one since it does not indicate the Bosch brand.
What do you guys think? Any Help?