I used to play a deck like this, and there's one little goblin I'd like to recommend. Weighing in at a mana cost of only two,
Goblin Piledriver will be a MAJOR addition to this deck. It has protection from blue, rendering it safe from their bouncers and tapping effects. And it also gets +2/+0 for every other attacking goblin. Save up your forces, bring out
Goblin Piledriver, and you could swing for a massive hit. One other card is
Goblin War Strike. This one cost sorcery deals damage equal to the number of your goblins. If everything runs smoothly and optimally, you can bring down your opponent without even swinging.
I'm going to suggest taking out one Krenko. At four, you'll likely draw him too much and be unable to play him. Three would be an optimal number. Just something to consider.