RIP the fucker that is BRANT.. What you have described is exactly what I was experiencing. Same WRX model etc. In the process of investigation I upgraded the Fuel Pump to a Walbro. That didnt turn out to be it & I was stumped to why it kept on occurring, until Mao from Evolution R sorted me out by having the section of the Brant removed that cuts the Fuel. (Went Faulty & is very common)
Have not had a single repeat since it was sorted by Mao. Top work & I suggest you do the same
