Are you saying that this started happening after you replaced the throttle body gasket? If so then that is almost certainly the issue. Those bolts have torque specifications - did you use them? Was this an OEM-style gasket or did you maybe cut one? Did you clean the throttle body while it was off?
Other than that you look for whatever little vacuum line you forgot to hook back up or the clamp you didn’t tighten or things of that nature.