In march of last year, I garaged my 98 civic lx (d16y7) and went on an 8 month deplyment to the middle east. I got back in october of last year and from the moment that I started it up, the idle has been going between 800 and 2000. I have been trying to figure it out ever since. It throws out a P0505 code (IAC) so I replaced the IAC, but even with the brand new IAC, it does the same thing. I have made sure that all my vacuum hoses are connected. I have replaced the primary o2 sensor as well. Any suggestions? BTW, is it true that air bubbles in the coolant can cause this condition?