V-6 with fuel injection has distinct stumble upon opening throttle, in neutral standing still and really noticible when in OD. After coasting behind traffic, there is a brief lag on acceleration and then clears. Almost as if it were loaded up. Also the plugs suggest running rich. The car has 100,000 miles with original sensors. No trouble codes. Oxygen sensors look good ??
Any ideas would be apprecciated.

With 100K on the car, I'd replace the O2 sensors, or maybe find a person with a scan tool to read the sensor output while driving. This will show a lazy or dead sensor.

had the same problem with a camaro 3.4 of my friends it was the catalytic converter makeing it run rich