Too fast idle

My throttle bore was filthy! All fixed love this site.

My 2001 Buick Century has approximately 85000 miles. It intermittently goe sinto a very high idle and after driving for awhile, starts shifting rough. These two do not seem dependant on each other, but each is becoming more frequent. The high idle occurs in the mornings when first starting. If I shut it off and restart a couple times, it will idle normally. It also happens while driving down the road. The rough shifting usually occurs after driving a bit and seems to be more prevalent in warmer weather.

I also want to add that the Service Engine Soon light comes on intermittently and when shifting hard, sometimes it makes a whining sound.

Thanks again.

My question is, what does this sound like to you and in your opinion, what would be an average cost to repair this?

Thanks for your time.

Hello, I have a 99 Buick Century and recently I have experienced very high idle speeds and erratic shifting issues. I have cleaned the IAC valve, and did notice my throttle body was rather dirty on the inside. I had cleaned the throttle body with a cleaner, cleaned the IAC, and started the car. The idle was still high. I disconnected the IAC, the TPS, the air box sensor, the sensor on the air intake tube and the EGR sensor, I thought the car should have shuddered or something, so it ran high still. I connected all the sensors back, started the car and still high. My next thought is to disconnect the IAC alone, then the TPS alone. Is there anything I am missing? I have seen others with the same problem, but have not seen any sort of resolution. I thank you for your assistance.
Dennis

I have not cleared the codes yet. I will have to go to Autozone to have them cleared. I also found the fuse for the O2 sensor was blown too. Might be possible I have bad sensors

If the codes are not cleared will it still have an effect on the idle speed? The check engine light seems to come on and go off intermittently

Ok

Codes: p0134, p1635, p0401, p0101, p0108
To negate most of these prior to these codes the only one
I knew was probable was the O2 sensor code due to finding a blown
Fuse in the engine elect panel. I had disconnected every electrical
Connector on or around the top of the engine near the throttle body (map sensor, tps, iac, egr). A total of 5 connectors to see if there would be a change in performance and there was none. The one thing I have ordered is the PVC line assy because its bad. Won't tell you what the previous owner used. Would this line from the evap canister to the PVC cause this problem or do I have issues with the iac or tps? The iac was cleaned with no change less its internally shorted.

I cleared the codes today. I've ordered the evap/PVC hose an it should arrive tomorrow. So I'll know what happens. That hose caused my problem? Guess ill see tomorrow.

Will let you know definitely tomorrow. The PVC connector end looks like a plug boot cover that was put at the end of the tube. It also causes a whistling sound I think the boot that was used I too soft and causes the "cap" to collapse hense the horrible sound in the engine compartment.

Replaced PVC tube, idle is much better. Computer must still be learning fuel mixtures and shifting is much better with some sluggishness. The old hose was loose on the vac connector from the vap solenoid. Will see how things work out after a few trips. I do still wonder about the IAC. The maintenance manual shows the removed position of the actuator so ill look into that next b

Codes cleared still high. Will look at possible bad IAC