Service Engine Soon: Code P0171

[hansoac]

I'm back AGAIN!! I had a post about how the car wants stall when it starts after it sits overnight. Well I took it to Nissan and "everything checked out OK". Well 2 days later my check engine light came on and I had a code reader hooked up..the Code being P0171 Definition Fuel system lean bank 1 and bank 2
Probable cause: 1.Low Fuel pressure 2. Blocked Injectors 3. Large Vacuum Leak 4. MAF sensor fault
I looked up this error code before posting this and most people are saying it is a loose/not fully tight gas cap. I checked that over and over.
ANOTHER thing I noticed is that if I get on the gas aggressively, the car will studder at about 4 .5 RPM's. it is frustrating!! any ideas??

I also tried injector cleaner and making sure my air filters were seated ok.