I wouldn't think it'd be timing. It's intermittent. Something is moving or getting hot or shorting out... Someone on another board said they had something like this too and had a rattle and was running fine but when the CAT rattle stopped, the cutting out and problems started. He punched a big hole in his CAT and it cleared up. Maybe a stopped CAT, not sure if you replaced yours? Maybe just disconnect it from the headers and see if it fixes it. Maybe some aftermarket electronics were put in and something is shorting out? A remote starter malfunctioning? I hate to mention anything if it causes you to replace a bunch of stuff that doesn't need it.

 

After doing someresearch to answer someone elses question today, I'm going to look at my injector timing. There is apickup assy in the distributor aka Camshaft Position Sensor. It is used by the PCM to control injector timing. I know all the injectors and all the spark plugs are firing, however if the timing signal is off, it will run like...
I'll let you know how I make out.

**UPDATE**
Camshaft Position Sensor is fine, truck still throws a fit at temp, then straitens itself out and runs great.
I think the only two things left that it could possibly be are the Crankshaft Position Sensor and the PCM.
Everything else has either passed test or been changed.

 

Mine was timing chain