I need help please.

My 2010 MK6 118TSI 2010 GOLF done 15000km. Yes only 15000km. Garraged for 4 years as i was interstate. Had some clicking noise few months ago. Then occasionally it would go into the limp mode, namely wouldn't allow more than 3000 revs. Especially if I drove it a bit harder. No engine check light appeared so i thought nothing of it. The other day it did the same thing but yellow engine check light came on. Now it will go over 3000 revs twice in the morning when cold and engages limp mode for the rest of the day with Yellow Engine Light on all the time. I have read hundreds of threads and a lot of them point to the N75 valve. Worth mentioning that i found a small coolant drops on the garage floor twice in the last three months. Very small not even a shooter glass combined. Coolant may be something totally different to what i have described above.

I would sincerely appreciate your help.

Thank you.

Zak