Random cutoff

Hello, Evo 7 owner here, I have question and curious if anyone has some insight on this issue. My car has been modified, both by original owner and myself. What I have been noticing is an issue where the car will turn on but the engine won’t turn over at times. I feel it is somehow in relation to the temperature as hotter days it will do this more than early mornings when it is cooler. The secondary issue I have ran across is a split second power cut of some kind. My tuner built into the tune a boost cut, where if the engine’s coolant reaches a certain temperature the engine would do a short power cut. For example, I was driving up a hill at near 3500rpm in Hi-boost mode and the car did some sort of short power stop, the car did a loud bang from the exhaust, then the car shut off, the CEL flickered for a few seconds, but I was able to turn it back on and car continued to operate as it normally would. What I have also noticed is that at really hot temperatures in a low cruising idle, the car may drop RPMs very quickly to 0 then go right back. The latest modification was a custom speed density build where the maf was taken out and a custom fabrication was installed. I did recently replace the radiator fan (the one in the front of the FMIC) but this was after the issues started up. A random AI-Google search points the finger at the ignition starter switch (seemingly easy replacement, with a video or two on how to do found online), or the crankshaft position sensor.