2008 Tucson 2L FWD 190.000 klm missfire

[abeautifulmind]

Hello to everyone.This is my first post here and I like to ask you guys if anyone expirinced the same or similar issue in the past.I am having a p0304 code missife for the past few months on my 2008 Tucson 2L FWD 190.000 klm.I bought in may 2020.I have changed spark plugs and cables.Did a compression test in the cylinder Wich showed good.Swap the coil pack to see if the code transfer to another cylinder (Wich it didn't).Used 2 times a very good fuel injector cleaner(bg44k) and the check engine light still keeps giving me the same code.The car since the beginning is not stalls or hesitate.My mechanic can't find it and we don't won't to start changing every part that might cause it(too expensive).I even tried the Hyundai dealership 2 days ago and the couldn't find a missfire or any data(maybe because my mechanic was clearing the code after every check).both the dealership and my mechanic said it is not a vacuum leak because it would show another code not p0304.Any ideas what might cause it or what to check? could it be electrical issue ? P.s. I am replacing my vvt solenoid this Monday along with oil change .Can the vvt solenoid (sensor to control oil in the engine) be causing missfire?