Found this answer through Google, hope it helps:

P0087 is fuel rail pressure is too low
P2178 is system too rich off idle
P2127 is possible issue with the powertrain control module

So I'd 1st replace the fuel filter if you haven't already and also check over the electrical connections to the fuel pump , also consider replacing the fuel pump relay and check that its fuse isn't cracked or corroded

If this checks out OK then use a mechanical pressure gauge to measure the actual fuel pressure and confirm that it is low or not

let me know what you find