considering you've said you could maintain 377 watts for 28 minutes before, im going to go out on a limb and say you didnt break too early or too late, you just plain broke away at the wrong time. being able to read a race is something that will come with time for most. as a random example, one of the cat4 crits i did this past summer i broke away solo with 7 to go, a guy bridged the gap with 3 to go, and together we finished 1/2. my best 30min power i was putting out in training at the time was around 250ish watts i think.

as for tips on reading the field, id suggest paying close attention each lap to where the pack slows down, speeds up, what part of the course takes less effort to gain position. in the 4's i found that gaining position to be pretty easy because nobody wants to drive the pace really since most are sitting in for a sprint. i used this to my advantage and broke away a little further back in the pack than i normally would to throw the people off at the front even more. there's also a ton of other little things to look out for, but those are some basics ive picked up that have worked well for me. granted ive only been riding for about a year, so there's still a ton i dont know that im sure others here could expand on. im like you in that i know i will not survive a sprint, and id rather come in last than having not tried my best for 1st.