I do run a bit at EZ pace, unless what you're saying is I'm going too fast for my EZ pace?
I ran 6 miles on Sunday at 9:20 pace (EZ)
Monday I did a 6-mile tempo
Tuesday I did 8 at slightly faster EZ pace (1:07-ish), or 8:28 pace.
Wed. I did the 5k trial
At your mpw, 8 miles is a long run. You did a long run the day before a time trial.
No wonder the time trial didn’t turn out well.