My Subaru feels sluggish & shakes when I drive it.

What is your question?

I gave it a tune up and three mechanics later. They still can't give me an answer. They hold my car all day and in the end they tell me. Well it could be this, that, or maybe something. Everyone is afraid to work on my car. Today they said the diagnostic didn't pick up anything. So they think the coils need to be changed. "They Think" that's over a $300.00 job for two. The car is sluggish, it feels like it is about to shut down, but it did shut down once but I was able to turn it back on fast. Also it shakes when I drive it pass 55 mph. Three mechanics and they can't tell me what is wrong w my car. I am about to go to mechanic school to learn how to fix my own cars!! :/ so frustrating Shed any light pls Thank You

What makes this problem better or worse?

it shut down and it's sluggish like it is about to shut down

How long has your 2011 Subaru Forester had this problem?

two months