Noises problem
1997 Vauxhall Tigra 4 cyl Two Wheel Drive Manual 117985 miles

hi my vauxhall tigra strugles to start up and i need to apply alot of gas for this. but when the engine is running, it makes a large hissing noise near the right hand side of the engine, just above it. the noise can be heard mainly near the last spark plug on the right and inbetween some other wires.

the engine also judders when idling and you can tell it really struggles to keep on running.
could this be a problem to do with the fuel injectors or vaccum lines?

p.s does an oil leak mean the gasket is cracked abit and oil leaks through to piston cylinder