stalling

Hello , i have a 2000 mercury grand marquis ,  i am having a on again off again problem .while driving  the engine stutters then dies .
it starts right back up . the check engine light and the trek light come on .
when i stop at a light it wants to die . if i take you foot off the break the car lunges forward, but does not stall.
then i drove it for two weeks and it was fine ,with out side temp at 114 , with the air on ...
it did it  again last night , while going up a hill , it kept studering  , and then lunging  when i gave it gas.
when i applyed the break the car wanted to stall. when i stoped at the light it did stall
but i drove it homeand it was fine , with the air on  and the outside  temp was 107 ....
i went to auto zone  and o'riley's and a friend has machine ..... but No code...

HELP


I have replaced ;
fuel pump. filter  ect
raderator . water pump, thermostat , hoses
battery
did the breakes and tires in sept.
regular maintance

Thank you for your time ... and have a great day
                                                                             vicki