Coast down idle speed and idle question ..

[Vette73]

After I had the porting work done on my 91 I find it sometimes idling a little high..
At start up the car is a solid 850.....When I'm driving I notice sometimes the idle is maybe 1,000-1,100......I read the coast down idle speed is 1,200 at 20 MPH and I am right at that....I just notice sometimes it stays at 1,100 and at other times when the car comes to a stop the idle will come down to 850, maybe 775 at times but no less...

If I stab it at times it will adjust from 1,000 to 850...

The weather has been clear in the northeast ( optimum driving conditions) no humidity and good clean air so maybe it's idling at times a little high because of this?

Just figured I would put it out there because I really can't remember if my car was idling this way before the porting work...I know Hot engine idle is 650 but does it change now the car has headers, exhaust and porting work?

Don't think it is a vacuum leak because the car dies correct itself most of the time...

Car is definately more responsive with the porting work...

Anybody have these issues if you want to call it that, with there ZR-1s?