I googled "Harley IAC" and got a link where a guy was having erratic idle problems, opposite of mine, his would go low and then jump back up....he sprayed carb cleaner into the IAC port and a lot of black gunk came out. Then his idle smoothed out. Do you think it would be safe to try that??
It works if the IAC port is gunked up and an '03 would have enough miles on it for this to be the problem.