Rev at startup
 

When I start my car in the morning or after it has been sitting for a while (2006 RX8 manual) it wants to rev up to 3k rpm and after about 30 seconds or less it goes back down to operating idle, all this happened after I found a broken vacuum line and replaced it for one off my parts car. I found a vacuum port and capped it off and that didn't help is this even a vacuum problem?