Hi, so the past weekend I noticed cylinder 8 failed the balance test so I did a compression test on all cylinders, checked spark plugs plus wires and took intake off to check injectors and everything came out good. Once I put everything back together and started it up without the IAC plugged in, the idle hung for a second at about 1k rpms and then shot up to 3k rpms and stayed there and at the same time a noticable thumping sound started coming from somewhere inside the engine and was pretty rhythmic where it thumped every few seconds. I am a little lost as to what this could be and was wondering if anyone else experienced anything like this.