running on 2/3 cylinder?

[FZR_600_90]

Last week , i was driving and my front brake were gone, so i decided it was time to work a little bit on the bike since its getting pretty dangerous to drive...so i finally install my r6 shock that i bought 1year and a half ago, bleeded the front brake, when i was putting everythings back together i noticed the ground wire from the battery was loose so i took the time to weld it good, it fixed my turn signals who didnt worked properly. I took her for a spin but not it seems like it isnt running on 4 cylinder with the typical subaru engine sound...a friend told me to spray wd40 on the headers so i get to know wich one are running but thats about what i would do first, no oil in overflow bottle but the engine is leaking oil and needs aome new gasket, still before that i was getting misfire and poor accélération on full throttle pull

[FZR_600_90]

Changed spark plug today, the wire are in a bad shape, spark plug from cylinder #2 was smelling gas so im looking for fire problem