RPMs Jump @ Cold Start in 4.6L | Ford Explorer Forums - Serious Explorations

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RPMs Jump @ Cold Start in 4.6L


August 7, 2014
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City, State
The Thumb, Michigan
Year, Model & Trim Level
2003 Explorer XLT 4.6
A few days ago, the RPMs on my 2003 Explorer with the 4.6 started jumping up and down at a cold engine start. The RPMs will continue to jump for 5+ minutes. If you put the vehicle in drive or reverse during this, it will lunge forward (or backward) as the RPMs jump. The RPMs will stop jumping after the Ex has "warmed up".

I replaced the IAC and TPS within the past few months due to a stalling issue.

I’ve cleaned the MAF and throttle body, as well as all PVC tubes and lines.

I have sprayed carb cleaner for holes/leaks and have not found any.

The Ex isn't throwing any codes either.

I am at a loss for what could be causing this.
Any help would be appreciated. Thanks!

!!! update !!!

I adjusted the idle set screw on the IAC and so far, so good. She idles around 800-900 RPMs now. The idle jumping hasn't happened in a couple days and here's hoping it stays that way!