1998 Vauxhall Vectra oil in inlet valve

1998 Vauxhall Vectra

getting blueish smoke from back end when accalerating took hoses off from inlet to the carb and was full off oil and the pipe going to the air filter just the short 1 before the air box, cleaned it all out week later oil and smoke their again how and why is the oil getting to the carb, is my engine about to blow our is salvageable, also have noticed lack off power as well when trying to accelerate then smoke screen. Any help would be grate full and instructions on how to fix thanks in advance