I just looked back through Intergalactic Truckstop to see if I've been guilty of Gontermanatopoeia (I love coming up with portmanteau words on the spot) without realising it at the time. I think I've managed to mostly avoid it, although occasionally I have a written down "*twitch*" when attempting to denote a character twitching their foot or antenna. Not so much onomatopoeia as signaling the motions being acted out, I guess.
Other than that, I've gone out of my way to avoid doing that with noises. When it comes to guns I tend to use "KRAK" or "PAF" or "POW", typical gunfire sounds like that. Also I was guilty of intentionally using "DAKKA DAKKA DAKKA" to simulate machine gun fire (or sub-machine fire, if you prefer). Also I used "KRAKOW" as an explosion sound effect once.