Gaz b

hi all im new to this just signed up today so go easy on me please!! need help...ive got a 2003 uk 350z not had it long bought second hand. was parked up at the lights engine running but no power in the throttle took to a garage was told the throttle sensor was gone thats the code that came up. ordered the throtlle sensor part of ebay it came the garage fitted it still no joy?? the engine yellow light still on and the traction light as well is on i think and it keeps dropping to below 1000 rpm and the cuts out? not sure what else to do any ideas or help wouldnt be great?