Bad injector, head cracking, fuel system restriction, bad injector cups, or fuel pump seals.
It could be a bunch of things, but I would start by inspecting your injector seals.
The 2013 Volvo C70 has 20 valves.
The 2013 Volvo C30 has 20 valves.
The 2013 Volvo XC60 has 24 valves.
The 2013 Volvo XC70 has 24 valves.
The 2013 Volvo S80 has 24 valves.
The 2013 Volvo XC90 has 24 valves.
The 2013 Volvo S60 has 20 valves.
The 2013 Volvo C30 has an inline 5 engine.
The 2013 Volvo S80 is a gas-powered vehicle.
The 2013 Volvo C30 is a gas-powered vehicle.
The 2013 Volvo C70 is a gas-powered vehicle.
The 2013 Volvo XC70 is a gas-powered vehicle.