  We have synthesized oxygen-deficient fluorine-doped samples of nominal
composition PrFeAsO$_{1-x}$F$_y$ to study the normal and superconducting state
properties. Resistivity of undoped PrFeAsO exhibits a strong anomaly at around
155 K due to the spin-density-wave instability. Fluorine doping ($x$=0.4,
$y$=0.12) suppresses this magnetic instability and drives the system to the
superconducting ground state with superconducting onset temperature 50 K. The
behavior of normal-state resistivity changes from $T^2$-like to $T$-linear to
sublinear in $T$ with increasing temperature indicating that both
electron-electron interaction and electron-phonon interaction are strong. From
the analysis of $T$ dependence of $\rho$, we have estimated the electron-phonon
coupling strength ($\lambda$) to be quite large (1.3).
