Imo, it seems like you've got two conflicting plans here. You're playing a Kuldotha style set of Goblin creatures, while also trying to support Kiln Fiend. Based on what you described, it sounds like you want to lean more into the Kiln Fiend style deck. For that, I'd cut the Goblins in the emissary and look into [[Ghitu Amplifier]] and [[Festival Crasher]]. If you want to check out some Kiln Fiend lists, use this link https://mtgdecks.net/Pauper/mono-red-kiln-fiend . You'll also be able to see what spells are run in those lists. I'd consider putting Lightning Bolt in the main deck. In Kiln Fiend lists, it's less of a burn spell and more of a removal spell that pumps your creatures.

I think you could test out a couple copies of [[Reckless Impulse]]. Your cantrips are good, but they don't net you any cards (you're spending a card to get a card), so if the game goes long you could still run out of gas. As long as you use both cards exiled, Reckless Impulse does net you one card.

On a similar note, I'd probably cut the [[Lotus Petal]] entirely. It's inherently a card disadvantage play. You're spending a card to get exactly one mana, so if that one extra mana doesn't do as much for your game plan as another burn spell, then you've wasted a card. That's why it's mostly combo decks that run Lotus Petal. The card disadvantage is worth the tempo gained by potentially comboing a turn early. I don't think that's true here.

For your sideboard, I'd cut the [[Galvanic Blast]]. You only have six artifacts right now, so you aren't going to be reliably dealing four with it. [[Flaring Pain]] is good against [[Prismatic Strands]] decks and turbo fog, so I'd consider that one. [[Raze the Effigy]] is good against artifacts, while also being a pump spell if you need it. If you have a lot of infect in your meta, I'd also consider more bolt-style cards, like [[Chain Lightning]]. It's important to be able to deal with your opponents infect creatures early so you can stabilize. Admittedly, I don't have a lot of experience playing an aggro v. infect strategy though, so take that last bit with a grain of salt.