Cleaning your IAC (idle air controller) might help. The IAC is what provides all of the engine's air at idle so if the IAC is dirty enough to hang up, it can cause idle problems. If that doesn't help, you might have a bad TPS (throttle position sensor) or perhaps even your plugs need replacing. The TJ's OE ignition system was already exceptionally good as the factory built it and performance won't be enhanced with an aftermarket ignition system. Older Jeep ignition systems could benefit by a good aftermarket ignition system but not the TJ's.
And if you ever remove your throttle body, you can leave that spacer off since it doesn't do anything to help performance with the type of throttle body our TJs use.