Hyundai Repair: 2003 SANTA FE STALLING, crankshaft position sensor, gas cap

Question
3 weeks ago while driving on highway car stalled for a sec then worked fine. Week later idling at stop light, stalled, started right up. Took to AutoZone code PO446, gas cap is on. Ran fine 2 1/2 weeks, no CEL. Then when driving 60 mph lost power let sit for 5-10 min started then cut out. Towed to service, started right up but CEL still on. 2003 Santa Fe 4 cy , 81,000 miles.

Answer
It sounds like you've got two problems, J.  P0446 means that you've got vacuum in the fuel tank (either the purge control valve is stuck open or the evaporative system isn't venting properly).  That shouldn't cause the engine to stall.

As for the stalling, my initial thought is that the crankshaft position sensor may be faulty but not setting a code yet.  Or it could be an odd fuel pump issue.  Or a host of other things, really.  When the problem happens frequently enough, perhaps take it back to service and suggest that if they cannot duplicate the problem that a technician drive it home and back for a few days in an attempt to make it happen.  I think feeling the condition occur will be the most instructive thing for the service technician.