4.0 sohc falling on it's face for a millisecond...?

[2000StreetRod]

intermittent electrical connection?

I'm considering an intermittent electrical connection. If it only happened when cruise control was engaged then it could have been the clock springs in the steering column. Maybe the motor mounts are worn and when the vehicle turns to the left the engine leans to the right straining a wire with an internal break or a bad connection. It could be associated with ignition (crankshaft position sensor, coil pack, spark plug wires, etc.) or fuel (MAF sensor, TPS, camshaft position sensor, injector wires, etc.). Does the engine hesitate when you stomp on the accelerator pedal while traveling in a straight line? Have you tried rocking the engine (when not running) from side to side to check for loose mounts?

 

[2000StreetRod]

locked torque converter

At cruise the torque converter clutch is usually locked so the engine rpm will not fluctuate significantly in a brief instant. There would be a jerk in the drivetrain because when the engine loses power the momentum of the vehicle rotates the engine via the driveshaft.