My 99 dodge ram 1500 doesn't like to idle when I first start if the motor is cold and the outside temp is below around 40deg. i have to hold the pedal down to around 1000 rpms til it warms up. and

SOURCE: 2000 SL-1 fast idle problem during cold weather only

You need to check and/or replace the thermostat and/or the temp. sensor. Take a meat thermometer and stick it in the overflow tank. The temp gauge on the dash should register above the 1/4 mark after at least 15 minutes of driving. If so, the meat thermometer should read above 180 degrees. If the meat thermometer reads 180 but the gauge isn't above 1/4, then you need to replace the sensor. If the meat thermometer doesn't read 180 or higher, then you need to replace the thermostat. The thermostat in these cars, though it doesn't fail on its own, has an unnecessary rubber gasket that fails, and allows coolant to leak past even when shut, causing the engine to not warm up thoroughly. IF the engine doesn't warm up, the idle won't come down--speaking from personal experience. I had to replace both items on my car. Now it idles fine, and after a bit of driving the gauge registers between 1/4 and 1/2, but always above 1/4. DO NOT tamper with idle adjustments unless you have exhausted all other possibilities. They are factory set, critical, and almost never need readjusting. Good luck.

SOURCE: 2004 Dodge Ram 1500 5.7 Hemi Quad won't start in morning

could be that the electronic throttle could be icing up. just remove the air cleaner and have someone cycle the key. the throttlebody will cycle prior to starting to do a self check. chrysler has a tsb out for this concern. tsb # 14-002-05

Marvin

• 85242 Answers
• Posted on Jan 13, 2009

SOURCE: dodge ram 1500 engine rpms surge at freeway speed

those sensors could cause the issue, clean the MAF 1st, also clean the idle system using the following procedure, the IAC can cause cruise surge. I use this to cure these problems all the time.

Here is the most common cause of surges and stalls and low idle, it is the idle speed control air-bypass valve (IAC) and throttle valve, they get full of gunk over the miles and cause idle issues (stalls, low idle) like yours, Get a can of intake cleaner from any local parts store, not carb spray, intake cleaner, it is made by a company called CRC, remove the air intake hose to the engine, hold the idle high so the engine won't stall, then spray the can of cleaner into the intake while keeping the engine running, use at least 1/2 the can, shut down the engine and disconnect the battery for 5 minutes, then restart and complete a number of mixed driving cycles, town, freeway, stop and go etc., after a few days the problem will go away as the system will relearn to the clean intake.

SOURCE: rough idle on 1990 saab 900 convertible, 16V

Because the car has adaptive technology, it may take a while to reset and adjust to the new, cleaner and better conditions than those to which it had previously adapted.

Did you change the cap and rotor? if the plugs needed replacement, likely they do too

Possible other causes include:

loose or corroded connections to any electrical component you disturbed (make a checklist and tick them all off as you check them);

mis-reinstallation of any F.I. part disturbed(checklist again)

obstructed water flow through the AIC valve;

improper voltage output from the AIC valve (for LH 2.4 systems, should output 8 volt at idle, dropping as load increases; for LH 2.4.2 system output 7 volt at idle etc; testing between terminals)33 and 17 at disconnected LH connector;

possible problem with MAF.

Hope this helps

Saabreur

SOURCE: 1996 Dodge Ram 1500 4x4 5.2L engine. Truck stalls

idle air controll motor is bad