Hello and welcome to JustAnswer!
What year, model, and engine do you have?
How many rpms does it jump up?
Ok great. I'm guessing it jumps up a few hundred rpm and comes back down every so often. The idle may also be erratic, up and down by itself. This is almost always caused by an erratic signal from the throttle position sensor (tps). This is on the left side of the throttle body with a 3 wire electrical connector, it tells the engine and trans controllers how far the throttle is open. When the sensor gets worn it creates very small voltage spikes. These small spikes tell the controller that you are opening the throttle when you aren't, and the torque converter clutch unlocks because it thinks you are accelerating.
The tps is on the left side of the throttle body held on with 2 t-20 torx screws. Its pretty inexpensive and very easy to change. Just remove the electrical connector and the screws and remove the sensor and pop the new one on, they even give you new screws. After you are done disconnect the battery for a few minutes to reset the minimum voltage values stored for the tps, and you should be good to go.