07 Lincoln towncar intermittently starts

Towncar cranks and then starts usually dies within
first minute. Sometimes it will start up and run fine
and other days it will start only to stall 30 seconds
later it seems to have more of an effect on rainy
days or high humidity. I replace mass airflow sensor
crank shaft position sensor and not long ago the
coil packs. Could this be a problem with the
ground? Not sure where to go from here