During acceleration rpms ramp up and stay. What is cause?

What is your question?

Sometimes during acceleration, my car may shudder. If I reduce my speed and accelerate slower it seems to be ok. But if I need to go faster, say freeway merge, the car will sometimes shudder. A couple of times I've noticed the rpms go up to 4-5000 and stay for a few seconds, at low speed- maybe 25-30 mph, and eventually changes gears, but I've usually slowed down because of the rpm noise. Again slowing down acceleration does help. I don't drive fast or very often and I don't go far. But the rpm sound scares me.

What makes this problem better or worse?

Acceleration may cause shudder. slower acceleration seems to help. Has only happened a couple of times.

How long has your 2009 Jaguar XF had this problem?

Couple of weeks