Been working on a 04 WRX was driving it and at WOT the car would not go over 50mph and then it slowed down to 45 then down to 35 and then 15 and will not go over 15mph. When at idle it idles a bit rough and when given gas the car just stutters, miss fires and sounds like fuel supply is being cut off. we have checked the fuel pump, swapped out injectors with known ones that work, checked for boost leaks and fixed them, swapped out coil packs, cleaned the spark plugs, changed crank shaft positioning sensor, also done a compression test and all cylinders tested out at 150PSI we have ran out of ideas to troubleshoot has this happened to any one and know what is wrong???