Ok the story.
I gotmy max 97 GLE put aftermarket intake. Car was choking then i put the original intake. about 1 month later after puting original intake back. Engine service came up, i begin to notice some kind of noise inside the engine when i accelerate like metalik kikin noise.
Cheked the ECU got codes for mainflow and knock sensors. Changed mainflow sensor metalik noise diappeared. But after reseting ecu i got engine light again with the code 10-1 front left htd 02 sensor heater and 3-4 knock sensor. Any one help is my car falling appart? Where can i get this o2 sensor cheap and instalation instraction is my knock sensor bed ? any help is apreciated.
By the way i raced today my friends and i lost almost to all of them i lost to 95 pontiac bonevile 3.8 not supercharged, i lost to 94 maxima se. I think there is something wrong with my car something with the air flow i feel like there is not enought air. No mods to any of these cars.

 

I think my gas milage decreased drasticly.i did 5 races all of the alittle bit less then 1/4 mile and i lost 1/4 tank.