So i hit the throttle and at about 4500-5000rpm, boost/fuel cut hits.
I initially thought this was misfire, but i am now more convinced that this is fuel cut.

It has been okay so far after so many fuel cuts, but recently, after the fuel cut kicks in, the car would suddenly run weird even during cruising. It made no power and literally sounds like a subaru broop broop brrropp brroop..
I reset the ECU by disconnecting the battery and it was fine. Only for a while.
After a few miles, it will go into that weird mode again.
I was never able to run the car smoothly on any trip more than 5 miles. It will keep going into that mode again (without hitting the fuel cut).
Reflashed the ECU, and same thing happened again.
Need help please. Thanks!

 

I had a misfire issue that sounds like yours, and it was just an ignition problem -- adjusted the plug wires, new plugs gapped closer, and finally swapped coils and that's what fixed it.

 

sounds like a limp mode, boost leak, crank sensor or MAF sensor

 

I found on mine that repetitively hitting fuel cut would toss out a P0300 misfire and make my car run strange too, very similar to what you described. Any CEL codes come up after the car starts to run strange?

 

No CEL code unfortunately. The weird thing is that the car will go back to this weird mode even after the ECU has been reset. Any idea how to fix this?

 

the subaru is it losing half the ignition. Aftermarket ignition amp?