Krenko is the first EDH deck that I made. I've had him for years and seen him go from causal to as cEDH as I could make him. I've powered him down just slightly from cEDH but he's good and I know what you need to make him good.
Firstly, you aren't running enough mana rocks. Krenko needs to krank and the faster the better. People are already going to try and stop you so oh well if you go out in front early, if you get shut down, it'll give you more time to rebuild. You want rocks that are low cmc so you can drop them asap. Look into running some of these:
[[Ruby Medallion]] and [[Cheering Fanatic]] (these are not Rocks but they makes Krenko cost less)
[[fell war stone]]
The thing is, you are running too many creatures. Krenko makes gobs, you don't need run so many. Focus on Krenko making the gobs instead.
I run all the cards that let me tap Krenko multiple times
[[staff of domination]]
There are others but these are a few you should make room for.
A couple of combo pieces you are missing are [[thornbite staff]] and [[mana echos]]. Thornbite goes infinite on Krenko with any sac outlet and echos will generate a ton of mana.
Two other mana power houses in Krenko are [[brightstone ritual]] and [[Battle hymn]]. These guys are good and there will come times when you are glad you have them in hand.
You are also not running enough card draw. Krenko stalls easy and/or needs to rebuild multiple times a game. Run cards like
[[reforge the soul]]
[[wheel of fate]]
[[wheel of fortune]]
A few great other things that I run that draw me tons of cards are
[[mask of memory]]
And the all-star [[slate of ancestry]]
You need redundancy when it comes to haste. Krenko needs to krank when he first drops. You should include
And [[mass hysteria]]
A few lands that I would suggest are
[[ancient tomb]] because speed
[[westvale abbey]] because sacing 5 gobs is easy and a 9/7 [[Ormendahl, Profane Prince]] is awesome.
[[mutavault]] because it's another goblin to double with Krenko.
[[Cavern of Souls]] because blue players hate gobs.
And just some other good cards I recommend are
[[ruination]] because you're mono red and fuck everyone who isn't. You could include [[magus of the moon]] for good measure.
[[Voracious Dragon]] to one shot an opponent.
[[Gamble]] gets you whatever you need.
[[possibility storm]] stops everyone else's game play but allows you to keep gob'n
[[crystal ball]] look ahead
Cheers, and enjoy krenking