obd2 scan code p1504 idle speed control inputs

check your air duct for holes as well as all grommets on engine, air leaks can cause this. the duct work is between the maf and throttle body for holes. also check if It 's installed correctly.

I checked the area described with a fine tooth comb, and can not find a hole or crack. I sprayed carb cleaner around the area with motor running to see if it would affect the idle, and it did not. the funny thing about this is the motor runs great and idles very good, with just a very slight change while idling about 7 seconds apart sometimes. Very slight. would not know there was a problem if the check engine light did not com on. I also changed the tps sensor when i changed the isc. don't think its drawing air there but can't say for sure. no variance .in idle when spraying the carb cleaner around it.Thanks, Bill

check your grommets on valve covers as well and then you'll have to have a pro check it with their scanner