2011 silverado 5.3. So this might be normal but I thought I would ask so today I noticed that when coasting and getting back on the throttle rpms will increase by about 500 then with in a second they will come back down I was going about 50mph didn't feal anything just happened to be looking. Did a little messing around if I am still on the gas but let almost all they way off and get back on it is fine it is when I am completely off and get back on that it does. I do have afm so I am hoping that it is a combo of afm and torque converter unlocking but I wanted to ask.

 

It sounds much like torque converter clutch operating as intended. The TCC will unlock when you are coasting with your foot completely off the accelerator, then lock back up when you step on the gas again. If you back off on the throttle but don't allow it to close completely, the TCC will usually stay locked, so you won't see the brief rise in rpm when you start applying power again. The slightly laggy TCC apply is intentional, in the interest of not making clunks, thumps, or surges in power delivery, and keeping your average driver happy.

I've only briefly driven one vehicle with AFM, so don't have much experience with its perceptibility from the driver's seat. I'm pretty sure it's fairly seamless on a completely stock vehicle... It does sound like *** with an aftermarket exhaust, and is not known for contributing to engine durability and longevity; but that's another topic for another 5000 threads.