BUZ71 MOSFET seems to be not fully activating
While your setup sounds OK, I suspect you're doing something odd. To begin with, a 30 ohm coil should draw about 1 amp (32 volts/30 ohms), so your current draw of 0.6 amps suggests that you've got a ground problem in your coil circuit. 

I assume you're using your 5-volt ground as your reference. Try activating your FET, then measure all 3 pins. Is the source reading 0 volts? What is the drain reading? Are you sure you've got your 32 volt ground properly tied to your 5-volt ground?