Land Rover Repair: 2004 LR Disco, crank sensor, purge valve

Question
Have been getting repeated evap codes.  Usually, putting silicone lube on gas cap solved the problem.  Now, that patch no longer works and code continues popping up.  I recently replaced gas cap, and that also didn't solve the problem.

Now, the engine has taken to shutting down intermittently.  It restarts after a couple of minutes.  Not sure if this is related to evap code.

Do I need to do a smoke test?  Any thoughts on what's causing engine shut down?

Thanks!

Answer
A smoke test would probably be a good idea.  Another idea would be to test the purge valve per the procedure in the workshop manual.  Apply power to it and see it it opens and closes with power applied and removed.  They often fail.  The intermittent shut down is almost certainly unrelated.  I'd start with a crank sensor for that if there are no codes