Bonneville 3.8l transmission noise

I forgot, it's a 2000 Bonneville. What about the torque converter? If I put it in gear, it acts like it is in neutral. lightly press on the gas, and it grabs like someone hit you from the rear.

Does is have all the other gears? Take it out on the hwy and make sure its going into overdrive. Also is there a check engine light on or was on? When you drive it get in and start it up put it in drive and wait a min before giving it gas. See if that helps at all. There could be a check ball in the vavle body that isn't allowing enough fluid into the torque convert.

Could also be the front "drive shell" is letting go. My 95 TransSport behaved a little like that before it decided not to go anywhere under it's own power in Drive. Had to replace the front"drive shell" along with numerous other parts in a complete rebuild at about 300,000km.

Problem was contributed to by a bad O2 sensor which caused the engine to surge violently at times.

No check or service engine lights. It will shift into OD, but it is shifting hard, or slow.

Strange thing was I was holding the brake in each gear, and let go a little, and all seemed well. Went into neutral, and it acted like it was still in drive. Think it is a sticking valve. Or oscillating valve.

Still curious about the bell housing.

Interesting thought. The O2 was replaced 14k miles ago.