Erradic engine situation

[surfwooder]

After a short stint on the Interstate, and short drive into town I had to stop at a downhill redlight. After stopping it felt like the engine was having convulsion. I recovered on it own, and I proceeded to my destination without further incident. About an hour later I returned to the car, and restarted it and drove to the Interstate without incident. I drove the Interstate at 80mph for 5 exits and drove on hilly, windy New Hampshire roads for 4 miles, to my home, without incident. Today, I scanned my Z4 with my Foxwell 510 for any engine codes, and found none. I expected to see fuel pump, injectors, coils, etc, but found none. Any ideas as to where to look? Thanks