Please help fellow stanger.

OK I have 97 GT and car is ideling really fu**d up. Gas is getting stuck non stop. For example if I drive in 3rd and my rpm's are 3K I can let off the gas and RPM's will still be the same and won't drop down at all until I brake. Then when I stop at the red light rpm's are still high for about 15 sec before they start to come down. CEL came on and code was #1506.

I've already changed IAC valve and adjusted TPS. But it is really messin up.

what to do next??? Car was tuned 3 months ago. But the problems started couple weeks ago. Thanks in advance.

yes the car threw the 1506 code before I changed IAC valve. So I thought it was IAC that's when I changed it and nothing. So I checked all hoses nothing I also went to the dealer they never heard of 1506 code "but the guy said it's IAC" Like I said when I drive car acts like it's in a cruse control mode RPMS are stuck always at same and never come down. Than when I stop at the red light they are stuck at 2K rpms for about 15 secs than they go down to 700 and sometimes even bogs down and dies. WTF

I doubt it but has anyone ever heard of code P1506 Idle Air Control Over Speed Error. When I told dealer guy even he said oh man that's the first one.