2500 RPM???....Thats really high...I would check out the IAC and if that isn't the problem then check possibly the TPS sensor. When mine started to go bad I was idling at around 1300 RPM.

 

do not use slick 50 its junk. sounds like a lifter to me on the idle the iac is probably bad syn. oils are alot cleaner.

 

well all the sensors are good, but i think its a vacuum leak cause i tried to stall the car by putting my hand over the air tube and all it did was almost die then idle really low

 

3000gt idle at 2500

my car having this problem before, then i went to the dealer to check.
They check it and say its the " Throtle body" The price to replace this part is 1100$, that too much money for me, im still in high school. So went to some place and bought the Use throtle body. THe use throtle body is arroun 110$.. and is very easy to replace it.