Cruise intervals- Zone 5 (for me 162)- 4@15 w/2min rest I think you are spending way to much time between intervals. And I'm not sure about your lthr seems awfully high.
I just starting doing intervals @ supermaximal(above max hr) Zone 5a (for me 173) 4@3 w/1min rest. Didn't finish first few time because I didn't want to puke on my garage floor.