Originally Posted by mountainmandrake
I did when i added a throttle body spacer recently.
There might now be a leak between the throttle body and intake manifold now which can be the cause of your high idle. Personally, I'd remove the TB spacer to see if that's the cause of the high idle via a vacuum leak installing it might have caused. Whenever there is a leak in the throttle body or intake manifold area, high RPMs are the result.
And actually, you got taken on the benefits of the throttle body spacer. There are no benefits to a throttle body spacer where a Wrangler TJ engine is concerned. No kidding. Spacers can perform wonders when placed under carburetors or the old no-longer-used type of throttle body called TBI (throttle body injection), both of which pass an air/fuel mixture, but spacers do literally nothing when placed under the air-only type of throttle body the Wrangler TJ engines use.
TB spacers do absolutely nothing for a Wrangler TJ engine. Really. No more power, no more MPG... despite the hype of some advertisements. Sorry.
And no guarantee your high idle is caused by having installed a throttle body spacer but a vacuum leak is a common cause of high idle rpms.