vq35SMASH

so heres the scoop, my stock t25 blew and i just replaced it with another one the other day and good news, no more smoke!! =] buuuuttttt.....now more problems arise... the idle was shitty like 500rpm's or lower but it would drive decent then it sounded like it was missing. also it backfires...alot, and loud, like gunshot loud. it does this every time i let off the gass no matter what gear im in. im afraid to get cop called for shots fired..lol. so i went to replace the spark plugs and when i pulled out the third one it was covered in oil. only on the threads and electrode. and from what i could see there was a little in the cylinder aswell. frustrated, i put the new ones in and when it was running(still rough idle) i unplugged the third injector and there was no change in the car AT ALL. so confirmed that the cylinder is missing right? so what i was thinking is that the oil could be coming from 2 places, the piston rings or sparkplug gasket, and since the oils on the plug im thinking the gaskets bad. and hoping its that too cuz its a easy fix. so i need some ideas from people if this has happened or they have their 2 cents on this?? any help is much apriciated THANKS!!!

AS240

order a valve cover gasket set and in the mean time, do a compression/leak-down test.