So, has anyone considered not allowing True Aim and Autofire to stack? It's a legal if questionable combination, given that the two are practically anathema to each other. If you're aiming, you're generally not going full-bore autofire. My players are nowhere near the level in the OP, still having less than 100 xp each, but if the problem is massive dice pools with Autofire, perhaps something can be done about that?
Rather than completely nerfing it, perhaps you could ask the current combat monster's player to forego using True Aim for the next two or three sessions, to see how it goes. Tell him that if he wants to use True Aim, then he needs to forego using Autofire. While they are a legal combo, they are thematically opposite, which should count for a lot in a narrative-based game like this.