Hi everyone,
I usually don't like to bother others for advice, but this time i really feel like someone with more insight than me could help.

I did my undergrad and masters in theoretical physics in the same city where I was born and raised (I am a EU citizen). After 5 years I got completely fed up with the field I was working on and felt like it was time to work on something else. Following my master thesis advisor's advice, I applied for many EE/CS PhD programmes in USA and UK, including top tier institutions like MIT, Stanford, Berkeley, Princeton, CMU and others. Surprisingly enough, I got accepted in one of said institutions, (I am not, by any means a stellar student, nor my GRE test scores were particularly good, so I wasn't even hoping of getting accepted to be honest).
After the initial shock, I accepted the offer and moved overseas. Having worked in a different field, I have asked a professor, whose research I was interested in, for advice. He told me that the courses I wanted to take were really bad choices, especially if I wanted to train for quals, and told me to take completely different courses.
This first quarter was a nightmare, for the first time I really struggled through every course, I was never really interested in the material, either it seemed trivial or really boring, but by the time I realized that, I couldn't switch classes. In the end I managed to end the quarter with a 3.6 average, and it was incredibly stressful.

Now comes the worst part: I horribly fail the quals, and I just hate the coursework again.
In addition to this I really struggle to find a faculty member who could be a potential advisor (yeah, I don't have an advisor), since they are either working on topics which I don't really feel suited for and also don't feel particularly interested in.

Right now I really feel like I should quit, as my preparation is probably not suited for the kind of research they are doing here, and my motivation is not enough to try to "close the gap" in knowledge, without knowing if I'll end up liking the research or not.

On the other hand I realize that I probably rushed my decision in the first place, and just can't get over the feeling of guilt that would come along with quitting, which is what keeps me going right now (though i realize this is probabily the worst reason to stay). I started my PhD a little confused to be honest and now I feel completely lost.

Any advice?

Hmm kind of a difficult one. What were your initial reasons for wanting to a PhD? If you stayed and finished a PhD, what would you want to do after? If you quit, what would you do?

Why did you fail your qualifying exam? Didn't you have to write a proposal and defend it in order to take the quals? Didn't you have to nominate a PI in order to do that?

My initial feeling is if your heart isn't in it, maybe a PhD isn't for you.