my 500 sec has the same problem . i also found all the same symptons that you have .i have also replaced the cap and rotor ....to no avail problem is still there .car also does not start in the cold. cranks fine has gas no spark.will start when weather gets warmer.have no idea how to check hall sensor in dist or the crank sensor or spark module...parts are very expensive donot want to gamble with my money....any one have any ideas or testing procedures....any help is gretly appreciated...thank you all in advance
james