Wondering why my 89 gta takes a long time to come down to an idle when i pull up to a stop light or when i push the clutch to slow down or stop, it does come down to a good idle just takes a while, is this normal or do i have a problem thanks.

 

mine sometimes takes about 2 seconds to idle down, but usually idles down right away when I slow down and press the clutch.

how long does yours take?
It could be a faulty IAC or TPS.

 

My car does the same thing. If I come to a stop real quick or sometimes even when im just stopping, the idle will jump up to anywhere from 1,500 to 2,500 rpm sometimes. Then sometimes it wont jump up at all. I did have a mail order tune done, so that may be part of the problem.

 

check the vacuum line that comes out of the brake booster i believe it goes straight into the plenum. check it for leaks/splits or the o ring on the brake booster might be bad. had it happen to me before but my idle was a little more affected by it cause it was a severe leak

 

Had the exact same problem on my lb9 and it ended up being the vacuum diaphragm for the cruise control. take a look around there for any leaks from the lines or diaphragm.