Please help! I have a 2003 350z with very Minimal mods.. short ram intake plenum spacer and cat back exhaust. The car has been sitting for over a year because I was redoing all the body work and interior.. the Car ran beautiful before I stored it and put the engine mods on.. now the issue I’m having

it starts and idles normal revs up normally.. but when I’m driving the car it’s fine until I punch it and it doesn’t wanna go over 4-5000 rpms sometimes it will drive normally but 90% of the time I have power loss.. I change the throttle position sensor and throttle body and reset the ecu worked decent for half the day but then back to power loss.. I have no check engine codes or lights at all.. I have called a few mechanics and always getting a different answer! Please help it’s driving me insane

 

Old fuel?