A couple of weeks ago, one of the bolts fell out of the connection where the tailpipe meets the exhaust manifold. Fixed that to learn soon thereafter that while I had a horrible exhaust leak that my IAC melted. I have a '90 with the 2.5 Orderd a new IAC, installed it just last night and now it wont high idle in the morning when I first start it up. Idles fine when it is warmed up, as compared to before when it would barely Idle. I adjusted the screw a little after work and hopefully that will fix the problem. Anyone have any other thoughts as to what would cause this problem? Also does anyone else notice the clicking when you shut it off?

 

Could be that you got a bad IAC.