Hi, i am a new player and during a game we had a couple of situations with the sun stroke attachment and other similar attachments

that i would like to make sure that were played correctly

One of the revealed plot cards was Power of Blood

Then during the marshalling phase opponent player attached sunstroke to one of my characters with a noble icon.

I chose to declare the attached character as an attacking character during the challanges phase and i won the

challenge by a total STR more than 4. Then according to the Sun Stroke my attached character would have his STR reduced to 0 for the rest of the phase but he wouldnt die because of the Power of Blood plot. The Sun Stroke attachment says that attached character cannot be saved but the plot card is not

considered a "save" , he just cant die, am i correct?

You have that exactly right. Unless it specifically has the word "save" in it, something like Sun Stroke wouldn't affect it.

Examples include Power of Blood, Bronn (Core), and Retreat (Core)