Sorry you and Sam are having a rough time Sue. Some cats just seem to get good # really easily, and others are more of a challenge. Especially if he isn't eating well, it makes it hard to know what to do. I find his #s a little confusing, the patterns are just different from those I am more used to, so I don't feel very comfortable giving you specific advice.
If I were you I would probably be at least considering switching insulins - when you've raised the dose you've gotten some unexpected lows so that would certainly concern me, but obviously this dose isn't working either. The benefit of some of the other insulins is they have a pretty clear-cut process to follow to know exactly what dose to give, when to change it, etc. It's not a magic bullet, but if I were in your shoes that's what I would be thinking about. I'm not saying you can't get him regulated on PZI, just that it's not looking like an easy road so far.
Anyhow... just my 2c. Great job getting a spot check in today, sorry the results weren't more encouraging.