I had the same problem on my 2000 after I replaced the stock throttle body
with a 68mm one off of a 2001. It took several months for the problem to
manifest itself, but once it did, it kept getting worse and worse. The truck
would idle at 3000 rpm, if I would put the stock 65mm back on everything was
fine. After doing some side by side comparisons of the the two I discovered
that the throttle body base was warped and it was not fitting flush against
the bottom of the o-ring that seals it to the manifold. It was about .010"
low in one corner and was allowing air in behind it, a light pass on a
milling machine and all was fine and has been for the last year.
Hope this helps,
-John
----- Original Message -----
From: <Sammon287@aol.com>
To: <dml@dakota-truck.net>
Sent: Wednesday, August 28, 2002 5:59 PM
Subject: DML: runaway idle speed on 2000 slt+
>
> My 2000 SLT+ 4.7L/ 5 speed has an annoying problem when venturing
offroad.
> It has done this since new, but since I rarely hammer the truck offroad, I
> have ignored it until now. When driving on a rough dirt road scattered
with
> small rocks, it feels like the cruise control kicks in, actually
accelerating
> up to 1500-2500 rpm. Stepping on the clutch lets the engine rev up to
> @2500rpm, which slowly drops as I come to a stop. Standing on the brake
does
> nothing to drop the engine speed, as it accelerates again as soon as I
> release it. Remember this is a man trans. I imagine this must be caused by
> some sensor/ throttle body actuator that is affected by vibration. This
would
> be a major safety issue if it was an automatic, but even with the manual,
it
> is impossible to drive smoothly on rough roads. I am reluctant to go to
the
> dealer (been there several times in 2.5 years) because they will never be
> able to recreate the problem. The truck wheels well at low speed (low
> gearing, LSD, and decent rear axle flex) as long as there is no high
> frequency vibration.
>
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