How to fix idle speed 2007 trailblazer - Chevrolet Cars & Trucks

First you need to have EBCM - electronic brake control module check for DTC'S - diagnostic trouble code's . If the light is on there is a code stored . I think most part stores can do this and for free . After you find out what code is stored , looking up that code in service repair information for diagnostic trouble shooting chart would be next step . There are a few codes too.
DTC C0035 or C0040
DTC C0045 or C0050
DTC C0110
DTC C0131
DTC C0161
DTC C0186
DTC C0196
DTC C0201
DTC C0240
DTC C0241 or P0856
DTC C0244 or P1689
DTC C0245
DTC C0283
DTC C0287
DTC C0290 or C0292
DTC C0455
DTC C0550
DTC C0558

Find the code do the diagnostic's , fix the problem , wiring issue's , a sensor , bad module ,what ever it is . The light will go out then . Here is a sample of code discription .
• DTC C0035 Left Front Wheel Speed Sensor Circuit
• DTC C0040 Right Front Wheel Speed Sensor Circuit

Usually means the engine bearings are worn out, or the oil pump is weak.
As the oil gets hot, it gets thinner, which reduces pressure. When the engine is at idle speed the pump is not pumping as fast as it is at highway speed.

No it would not ! you probably have a 2-3 Shift Solenoid (SS) problem !
You trailblazer has Vehicle Speed Sensor (VSS) located on the tail shaft of the trans . this sensor supply's info to the PCM for vehicle speed . Your trailblazer also has a Input Speed Sensor (ISS) if this were bad it would cause erratic shifts all gears ! Does your vehicle have a check engine light lit or any other type light like a yellow wrench or service vehicle soon ? Your best bet is to take it to AAMCO or some other ASE certified repair facility !

Problem with electronic throttle control maybe. Any light's lit on the instrument cluster or messages engine power reduced . Could be a sign a position sensor is going bad . The gas pedal assembly has to sensors as does the throttle body . You could try cleaning the throttle body bore . Having a qualified repair shop hook up a diagnostic scan tool to view sensor data would be a good thing .
007 Idle Speed Problems Scan Data for Idle
1 reason your cars throttle body needs cleaning Gain lost horsepower and...

I would suspect the clutch on the air conditioning unit, also if the unit is overcharged
from a recent charge this would also bog the engine. At speed it would not be as pronounced.
Hope this helps.

Did he check the oil? Is it low. It could have a big leak.

ref. link:
http://www.tbssowners.com/forums/general-tbss-questions/71077-no-traction-control-button-switch.html

To disable the Traction Control and Stabilitrak depress and hold the button under the large engage button on the shifter. There may be an issue with the idle speed adjustment for operating with the TC/S enabled.

are you reading your rpms right....5-6000 rpms should equal 70- 85 mph....that is certainly not idle speed....invest 20bucks in a Haynes manual----it is good reading

Here is the common problem and fix.

Here are some of the causes of surges, stalls at stops, slow idle speed, erratic idle speed, rough idle and engine hesitation (and other problems), it is in most cases the idle speed control air-bypass valve and or throttle valve and upper intake, these area's get full of gunk and combustion residue 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.

idle air speed controller.
dirty throttle body
air cleaner clogged
air flow meter
bad injector
leaking intake manifold
vacuum leak
bad plugs
ignition components