My car wont start sometimes, it will start then stall. Whats going on?

What does the code u1000 mean on the snap on modis? Ill go start it and itll just crank over. Then just randomly driving it, it will shut off or rather stall. Then start right up like nothing when you try to start it again. Ive had the battery, starter, and alternator tested. They are all perfect. I hooked it up to a snap on modis and 4 codes came up. 1st code u1000 is what worries me. Which means (class 2 data link). I dont know what that means exactly. Then code #2 cam shaft position sensor. (Which I replaced 2 months before all this. It still looks brand new and in working shape.) Could it be wiring to the sensor? Or a faulty sensor? The other 2 codes are emissions and o2 sensor port 2. I already know those. Just worried about the first 2 codes. Help?