Limp mode

[Sebas]

Hello, I recently started to have a problem with my car. Engine runs rough on idle (kind of like missing a beat) I've been told it's faulty injector. Today I was on slip road and my car lost a power around 3500 rpm and wouldn't go faster than 60 mph in 5-6 gear. As I understand it went into limp mode. Can this be caused by faulty injector? Or is it turbo I should be worried about (I can hear very quiet whistling when I am in 2nd gear driving around 20 mph) ? Thanks !