Tejae brown

Hi everyone, just bought a 350gt skyline and the engine light came on, I checked it through and just needed new coils. I replaced them and the car was running fine until about a week after where the car wouldn’t rev past 4,000 rpm. Since then the car has stared to missfire again and is struggling to get past 3-3.5rpm. No lights are on at the dash. Anyone have an idea on what could be the issue?