Electrical Issue?

Hi! I was driving the other day and suddenly my car would not accelerate anymore when I pressed on the gas pedal. The gas gauge then dropped to E (although it was at 1/2 tank), and my car shut off. When I tried to restart the car, it sounded like it was trying to turn over but could not successfully start. I had it towed to an auto shop, but they can’t seem to figure out what exactly is wrong besides a probable electrical issue. They have mentioned wanting to replace the ECM and fuse box. We are trying to figure out if anyone has had this issue before and what they did to fix it. To attempt to fix the car the auto shop is quoting me at $2,000, which is approaching the value of my car, so we’re hoping to be able to fix the issue ourselves. Any ideas or information is appreciated!