So, I pretty much bought all the best items in the recommendation tab and I still had like 5k gold left. Is there any item upgrades I am missing? I am new to the game and I don't know all the items in existence.
you can enchant your boots and also buy elixirs
sunfire and thornmail are the worst items
Okay, I do not play Malphite so I cannot suggest any items, but a few words of advice:
ALWAYS UPGRADE TRINKET. 
or 
if you need to help deny vision. PLEASE.
Buy Elixirs. 
for Malph I'd assume, but not 100% sure.
Do those two (mostly buy Elixirs after each back,) and you should be good. I think.
Edit: WELCOME TO LEAGUE BTW! I promise we're not all dickbags. [slayer-jinx-catface]
Tanks are tanks, itemize to their builds and champion kits but make sure it synergizes well with your kit. Yours is good in this game, Frozen Heart or gauntlet, sunfire or thornmail, you can even go abyssal with malphite if theyre heavy ap lol
This is the best site for finding optimal builds for champions. Sources data from high level games.
You can add me if you want to play :D.
