Help please

[caesarfolarin]

Ok so I have a P0420, P0442, and a P0303 code on my 2003 Buick LeSabre (3800 series 2 engine) And I think they are all related to one another...I've done lots of research and somebody said that one of the possible causes of the misfire on cylinder 3 (P0303 code) could be caused by a evap system leak which makes sense because the P0442 code is (evap system leak detected small leak) So I think that is the reason why I am seeing that random misfire on cylinder 3....Does anybody on here drive a 2003 Buick LeSabre that has had the same problem that could possibly help me? I think if I find out why i am getting the P0442 code and fix it I think that it will fix the misfire on cylinder 3

 

[MelsRegal]

P0442 does not cause misfires.
https://www.obd-codes.com/p0442

 

[HotZ28]

As mentioned, EVAP code/leaks can not cause random misfire on one cylinder! Have you checked the wire & plug on #3? Sum ting wong here!