ok my car ran real good for a while since the swap. its and ls in a 90 civic 4d. heres the problem after a while it got cold so like usuall. it would idle higher when the car wasent wormed up. after a while it would go down and all would be good. for the last few weeks the car has been idling higher and higher. one day it started at 2000 rpm then it has slowly made its way up to 3500 prm or maybe it was even at 4000 for a little while. its a steady idle. im pretty sure its a vaccume leak. i need to know what other posiblilties there are for this problem and how to do a leak test on a honda motor.