I 99 Chevy Trailblzr that starts hard when cold. Code shows bad fuel pressure sensor and purge valve solenoid?

Took it to a shop, they said it was a bad fuel pump. The fuel pump was replaced approximately two years ago so I am skeptical of the diagnosis. I took the truck home and after it sat overnight in the cold measured the fuel pressure, it read 55psi, is this a sufficient pressure to start the vehicle or is the problem I am experiencing somewhere other than the fuel pump?