Which version of the 1.9 diesel is fitted to yours? The engine code [F9Q-???] would help. Going by similar Renault faults; it sounds like the engine management's gone into "limp-home" after detecting a fault. Your best bet is to find a local garage that can read the fault-codes and get some idea of what's upsetting it.
Stuck-open/end broken off EGR valve; blocked particle filter; fuel-rail pressure sensor; high/low pressure pumps/relays; seized turbo; split intercoolers; bad connexions/earths; wiring faults - all sorts are possible on these.