I doubt its the CPS, the 6.0 doesn't have issues with it like the 7.3 does.......
If you let off, will it return to idle or die?
Check Engine Light?
Could be ICP, when the ICP in mine started leaking, it would do all kinds of weird stuff. Surge, lope, idle and die, or running down it road it would be like you instantaneously stabbed the throttle and then it was fine. Ron changed it at the 2013 rally and its been good!!!!
Plugged fuel or air filter? Is the air filter light on, on the dash, or the filter minder pegged? How many miles on the Fuel, Air and Oil Filters? Oil at proper level, low or frothing oil will cause issues just like on your 7.3. Low enough = NO RUN!!
Blown boot? That would make it run bad, and smoke like a freight train......
Is it gelling up? It was cold last night and this morning?
Check the FICM voltages with the scanner (if so equipped) or use this procedure:
http://www.ficmfixer.com/testing.htm
If the voltages are not right, it is hard to start, dosen't want to run, timing is WAY late (smells like you kicked a kerosene heater and tripped the shutter) late.... and when it completely fails you are DRT (Dead Right There). When mine died (thanks to a battery and alternator issue) it would only put out 12 volts, period... needs to be 48.... used the ficmfixer service and all is good again. Much less that a "Ford Fix".
Get a scanner and see what codes, that would get you in the right direction.