Misfire only when stopped or low rpm/ idle bumps

[talonm3982]

Hello all,

I got a 99 malibu that has had lots done to it in the past 5000kms. new muffler, new plugs and coils, new brakes, oil change recently done, not sure if it matters im just not super technical with this stuff. anyways, my plugs died due to really bad misfires all the time, and after the replacement it ran pretty well. however off the bat i noticed it would still misfire a little bit when i was either revving while stopped in park, or moving at lower speeds pressing the gas pedal too hard. so now, the problem is, that only when i am going slow, or just at a dead stop, my engine can misfire and it will bump sometimes while in idle. i had trouble codes checked for the engine light and it came up with two codes. po442, Evaporative Emission System small leak detected, and po137, HO2S circuit low voltage bank 1 sensor 2. does anybody know what could possibly be the problem here? any help would be good. people tell me to replace the sensor and that might do it but im just unsure.

[talonm3982]

Correction, not low rpm, just low speed. After like 10kms I'm safe and the engine runs normally

[maxwedge]

https://www.yourmechanic.com/article...by-jay-safford, diagnosis for 0137,