I have an 04 Buick century with an intermittent high idle. We can’t find a vacuum leak and I have replaced the tps and checked the wiring from it to the ecm. Not really sure what to check next. Any ideas?

How did you search for the leak? Carb cleaner?

Is the Check Engine light on? If so, what are the stored codes?

Have you disconnected the plug on the IAC to see what happens?

1. Unlit propane torch

2. No stored codes

3. No I haven’t. How do I do it

I think on the 3100 it should be on the firewall-side of the throttle body.

Here is a good video that should help for IAC removal on the 3100: I would after the IAC is removed have a peak down into the TB port and look for dirty carbon build ups.
A quick spray of Carb cleaner, on A Q-Tip generally lifts the grime off quick, but for a main spray thru into port,Throttle Body & MAF sensor safe is recommended only.