When driving my 2007 Pontiac Grand Prix gets a shudder around 1500 rpms

What is your question?

Shudders around 1400 - 1500 rpms but stops when I let off the throttle and push it back down harder than i was

What makes this problem better or worse?

Stops when I let off the accelerator or when I push harder on the accelerator

How long has your 2007 Pontiac Grand Prix had this problem?

Since I got the car a couple weeks ago