Seems like a cool build. You might consider Sunset Pyramid over Shielded Aether Thief. Without many energy producers, it seems really hard to make Thief a reliable draw engine. Not to mention you can run it out with Whir of Invention and sink mana into it even when it runs out of counters. Speaking of answers you can run out with Whir, Sentinel Totem/Crook of Condemnation Treasure Map and Aethersphere Harvester (which you can also fetch with Trophy Mage) are all cool sideboard answers for Graveyard decks, grindy control matchups, and Ramunap Red respectively that fit your theme perfectly.

Thank, I've considered Crook of Condemnation for the sideboard as I can recur it once set up, but I've generally already won by the time I get a nice big recursion up. The main issue I have is I really need Memory to refill my library as you can easily mill yourself here if you're not careful, so Sentinel Totem can ruin your own plans.

Aethersphere Harvester is a interesting suggestion, Shielded Aether Thief is mainly there to block not draw cards, so the energy is a little redundant. I test this but I may struggle to crew the Havester with only 4 creatures?

Ramunap Red is my main problem hence the very low end cards in the sideboard, It has quickly beaten this deck a number of times. God Pharoah's Gift & Approach are such a good match ups though, They are slow enough that I can get set up and then I have enough Mana to out control both of them, Grixis or U/R control that a little more hands on are tougher matches.