ACED are difficult. Most grade 5 encoded data is difficult!
Tip 1: Forget collecting it, find yourself another task - a watched pot never boils... you will collect ACED doing so many other things
Tip 2: Modify a CLASS A Sensor to Wide-Angle (88 degrees) - to max your chance of picking up any targetted ships data
Tip 3: Find a very high populated, high security system with a single star - fly out of the system far enough so that when you turn around you can see all the spawning ships in the system. Cycle around them, pick up all the data. Relog. Repeat
Tip 4: Go into a HAZRES, and just kill everything as per usual- in doing so, you will pick up a lot of data from targetted ships
Tip 5: As above in a CZ
Tip 6: As others have said, Anaconda's appear to be the best source - but other combat ships can drop them
There is no magic, it takes patience and you must prostrate yourself to RNGesus whilst crying "Oh Braben, We are not worthy!" three times.
But, if you stop ACED being your sole aim, they will come... Slowly... But they will come.