Hey everyone I have I issue with my rb20 to start with it has stock ecu custom front facing plenum rb25 turbo with bigger compressor wheel and op6 turbine housing welded wastegate highmounted, turbosmart external wastegate 35mm, walbro fuel pump and 32 gtr intercooler with piping to suite now my problem is the car will start and sometimes hold idle and when it does hold idle It hunts really badly revs go from 1000 to 2500 and just keeps doing it and I'm fairly sure it's not the air flow sensor because it will rev over 2500 with no restriction iv replaced the plugs and one of my knock sensors was broken so I got a new one iv cheeked all sensors are connected and iv cheeked for vacume leaks but can't find any I really need help on this one. What could be causing this?