That sounds like what it was doing. Its smooth as silk this morning through.
Depending on the connection it could be fine and then fail, causing the IDM to shut down an entire bank of cylinders hence the feeling it's running on only 4.
Try removing the oil cap and give it a sniff...do you smell burnt wiring?
Also the next time it acts up, with the engine idling disconnect one of the harnesses going to one of the heads. If it stalls, you've found the good harness. If it keeps running badly, you've found the faulty harness.