Engine Performance problem
2000 Subaru Outback 4 cyl Four Wheel Drive Automatic 130000 miles

Hello!
I have a problem with my 2001 Subaru Outback after replacing a fuel pump. The car is losing power and backfiring when idle. The fuel pressure was tested (40-45pci).
The car has new spark plugs, ignition wires, air filter and used coil which was from my other working car. My opinion is that thre is flooding fuel in the exhaust manifold, but I could be wrong. I tested pressure regulator as was recommend by a diagnostic act and it seems work normal.
The fuel return hose was broken during fuel pump replacing, but I repair it and that place looks dry and doesn't leak. When I fixed that return hose, I used a fitting that was a little smaller in diameter than the original hose. Can this new hose be the problem?
I need to make this car run, so any opinion would be helpful.
Thank you.