HELP!! 750i problem is still unsolved

I have a newly acquired 2008 750i brute force and it came with the a seemingly small problem but is turning out to be widely unsolved. My machine turns over no problem it idles great and has full power for a few minutes but then I get half to a quarter throttle and it sputters and backfires a bit. But the most confusing part to everyone I've encountered is that if I hit the kill switch twice really fast it has full brute power for a small amount of time. I've talked to mechanics and brute owners and they are stumped. Even a Kawasaki mechanic with 18 years experience are at a loss. The fuel pump was changed and a in line fuel filter was installed. New wires, new coils and new plugs. My only idea is maybe the Tps sensor but it's supposed to be bulletproof but I'm running out of options. There are lots of threads about this but the problem never seemed to get solved. Please anyone that can help me or give me any ideas where to look would be appreciated.