I got a 2007 Chevy cobalt ss 2.0 superchargered I’m having real trouble with a p0171 code I just swapped the motor out and put a new one in randomly. I’ll get the P0 171 corresponding with a P0 300 but I already changed out the plugs the coils and the wiring harness changed out vent canister solenoid. I’ve already changed out. The purge solenoid changed out the fuel filter. Got the Z ZZPerformance braided fuel line going to the fuel filter new maf sensor. Can someone please help

 

Any kind of mods? Intake and such? Its pretty common to see a P0171 after installing an intake. P0171 is either to much air, or not enough fuel. Check intake and intake manifold for cracks/leaks. Injectors could be dirty.