with this nice cooler weather lately my TBI has been idling very high when starting and it stay in that mode for prolonged times and acts like a carb ( you can mash the pedal and it drops down to normal) but then when you press the pedal again right back into fast idle .... This fast idle can get up to say 1600rpm and it will take a few miles before it decides to drop down and stay down ..... By cooler I dont mean 30 degree days maybe 70's but when it's like in the 80's and 90's the car doesn't do this.Or is this just normal, just kinda though a few miles at this elevated rpm was a little weird for an injected car no matter what.

 

1167

I would check the usual suspects:

Binding throttle shaft - cable.
IAC - clean it and reset it.
CTS and IAC

//RF

 

nothing is binding that I am sure of .... and no codes are being set
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just wondering if it could be the IAT sensor wigging out maybe and not throwing a code

 

Ive had this same problem recently in cooler weather. I have a 175 thermo in it right now. When I stop at a light it will idle about 1100 then take about 10-15 seconds to settle down to about 600-50. Im thinkin IAC.

 

well added a 195 thermostat and got my heat stove working right it had a faulty thermo switch and replaced my CTS car runs nice now doesn't do that high idle thing anymore. I think it was the lack of hot air more then anything in the air cleaner causing it.

 

No, it was the cooler thermostat. There is a table in the chip that designates the desired idle rpm vs. temp. At the cooler temp your chip was just asking for a higher idle.