hi im from Montréal and i put 50$canadian(full tank) of 1.04$/L 94octane gas.
last me 171 km??? its way too much last year the worst i did was 262km and i really beat the sh*it out of it this time.

My o2 sensor is a STANDARD(brand) new from last automn what else can be my problem. It dos'nt leak, smoke, and runs fine??? plz help.

 

General tune up is likely all you need. The O2 sensor is good for about 60,000 Km's.

You likely need new:
Plugs
wires
Distrubuter cap and rotor
Throttle body cleaning
Inspect all hoses and vac lines for cracks

A tank of gas should get you over 400 km's. Your car is way out of tune.

 

Plugs new spitfire
wires new 8.8 life time warranty silicone accel 300+
Distrubuter cap and rotor new accel
Throttle body cleaning???how???
Inspect all hoses and vac lines for cracks....thank i will.

what else missing for a complete tune up??

 

Watch some of that Accel stuff. I've had problems in the past and so have others here. Might be your problem.

Take off the TB. Remove the sensors and clean out the TB with TB cleaner. Any automotive place should have it. Comes in an aresol can.

O2 sensor and check timing is all that is needed for a full tune up. Everything else is beyond a tune up but we might have to go there.