P16NF06 MOSFET not triggering with 3.3V
The data sheet says that it is guaranteed to start to turn on (250uA) with 2-4V. So there is no guarantee you will not get a unit with high threshold voltage, and even if the threshold voltage happens to be 3.3V, 250uA is not exactly fully turned  on for most purposes.

Of course you might get lucky and find a particular unit that was closer to 2V so it sort-of works, but it's really bad practice to depend on luck rather than datasheet guaranteed values. This particular part is only guaranteed at 10V Vgs (0.1 ohm Rds(on)). '

Use a part that is specified at no more than 3.3V (1.8V and 2.5V parts are available) and you'll not have these problems. Most such parts are in surface mount packages, however there are a few in TO220 packages.