I have a 03 6MT Titanium Edition with 124K on it with the 2 dreaded codes PO300 and PO1800 I changed my spark plugs and checked all 6 Coilpacks they are all good I got a NWP block off plate to delete the VIAS to see if that would help but the code still remains I cleaned the MAF and changed the PCV and still have the same **** the check engine light blinks at idle only but ONLY at idle I recently found a giant *** hole in my O2 sensor and I was wondering could this cause my problem? I have video and pics to prove my issue here Thanks guys

 

p1800 is not related, so ignore that. Random misfire could be plugs or oil in the tubes. I'm not sure if over advanced timing could only affect idle or not (that would be a VTC solenoid).
I'm not sure what you mean with the O2, but if you want to rule it out just unplug it.

If you haven't changed the plugs, then do that.

 

Ive changed the plugs and valve cover gaskets still didnt change anything still misfiring theres like a massive hole in the Primary O2 sensor Bank 2 i feel like thats whats causing the misfire. I got a new Oem replacement Bosch one from pepboys gonna install it to see if that will change the results my maxima is 100% stock and i run 93 so i dont understand how this can be so much of a hassle to fix

 

I would change out your Primary o2 sensors, upstream.. Which is the one in the picture you posted and the one by the firewall. Get them from Advanced auto with 30-40 percent off code.

 

P1800 is the VIAS Control Solenoid Valve.

See page 638 - http://boredmder.com/FSMs/Nissan/Maxima/2003/EC.pdf