Yeah I feel ya Kiwi, I'm oldschool. I relate to a lot of your problems and major annoyances.
They just designed the game in a way that promotes a lot of frustrating gameplay. Camping is rewarded and mounting your gun is literally OP.
It's just making your peace with the game. What makes a cod fun for you?
Is it the just running about doing your thing?
Find a new thing e.g gamemode,gun,class setup, equipment Frags/C4 throw an RPG on and decoy grenades for randomness.
You just have to make the game more enjoyable for yourself. Camp every so often and earn a few big killstreaks if it makes you feel better.
Try sniping or just give something different a go.
Most times I play this game, at some point it will turn into a catatonic rage and serious self doubt on one's gun skill. Was it just me that missed a few shots? Was that guy any good?
*Proceeds to watch killcam*
"OMFG you cock sucking goat fucker! How dare you, you fucking skin of the end of Satan's Scrotum!" Game is fucking BULLSHIT! I'm done........ I'm gonna sell it!!!!!
Then at some point in the near future another night playing KC on Hackney yard and you earn a VTOL Jet without even barely realising. "Oh shit my proximity mine just hit a triple" Alrite! Sweet dude.
It's a game of 2 halves, quite often I'm on the shitter, dirtier side with the crack on it. Everyone once in a while I'm sitting on that other side, The rainbow with a blunt and 20 ho's. A nice 18 year old malt whisky to chase it!!!!