Hi all:

My 99 4.0 V6 has started having issues at low RPMs where the throttle will oscillate. This is especially noticeable immediately after starting, where the RPM will drop to below 500 and nearly stall, then surge up to around 1200, and fall back to almost stalling a couple times before stabilizing just under 1000.

This is especially noticeable when driving at low speeds and the RPM around or somewhat under 2000, where it will act as if someone is stepping on and then releasing the gas pedal.

Recently its also had a hard time starting, acting as if its not getting enough gas. I have recently replaced the fuel pump. This problem does not change much with engine warming, and at highway speeds the vehicle drives fine.

Any suggestions as to where to look? I'm not that much of a mechanic yet, but I did look up info on the TPS, and it doesn't sound like the descriptions others' gave of TPS issues, but perhaps I'm wrong...

Anyway, I'd appreciate any further input! Most of everything on the truck is still original, about 73,000 miles.

So, someone local recommended checking/cleaning the iac, which I did. That corrected the idle issues; the truck runs MUCH better now. However, there is now a whine anytime the engine is above 1,000 RPM. There were no vacuum lines messed with during the IAC removal/cleaning/re-installation. (BTW: I cleaned the IAC with brake cleaner per the local O'Ralley's recommendation.

Clean the MAF sensor too. If that doesn't help, I'd invest 20-30 into a diagnosis from a shop.

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2003 ram 1500 4x4. Laramie package. Quadcab. 5.7l Hemi. Leather interior. Infinity sound system.
*sold* 2002 Ford Ranger Edge. Reg Cab. 3.0 V6. Vinyl floors. Custom radio. 2wd. Fog light mod, air box mod, Toolbox, and blinker mod.

Hell while your there hit the throttle body as well. Carb cleaner.

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2006 Ranger. 2.3l 5 speed
Air box mod and throttle cable mod.
Tri-fold tonneau cover. VHT taillights. Tinted corner lights.
fog lights.black headlights.
LED driving lights, dome, 3rd breaklight, LED tailgate light bar and LED foot wells. LED tails.
4.10 stock gears[/COLOR]

My Build:

http://www.fordrangerforum.com/proje...ger-build.html

???? Are ypu guys serious?

Okay, you need a throttle position sensor. If that doesnt work, right on top of your throttle position sensor there is another sensor, forgot the name, but its metal and it is round. Has two screws on it. Those two sensors work together to feed the motor correct amount of oxygen and to keep it idling right. If ypu need pics let me know. Each sensor is 45 dollars and under. If you take it to a mechanic theyll charge you 450 dollars for a job that takes less then 5 minutes. If you dont know what im talking about youll take more time looking it up on google then actually replacing the sensor

We were just going with the cheapest option first. You want to clean everything and make sure there's no carbon built up. That could be causing your problem. If that doesn't fix it, then start replacing the obvious. Like the TPS or IAC. Or if that doesn't help, you may need a new throttle body.

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__________________
2003 ram 1500 4x4. Laramie package. Quadcab. 5.7l Hemi. Leather interior. Infinity sound system.
*sold* 2002 Ford Ranger Edge. Reg Cab. 3.0 V6. Vinyl floors. Custom radio. 2wd. Fog light mod, air box mod, Toolbox, and blinker mod.