My 2004 Trailblazer started idling rough today. We changed the battery approx a week ago. How can we fix this? Thank you.

Did you use factory spark plugs? Try cleaning the throttle body.

did any vacuum lines come loose.. check the emissions control lines for leaks..

I had a similar experience. Finally the car started overheating. Turned out the thermostat went bad and the radiator blew a leak. Had those replaced. Runs great.

on dodge motors
fitted a lot of parts and still no better

the fault code clears and comes back as a intermittent problem

could be electrical voltage drop off or heat related failure

i wonder if your 02 sensor ,the catalytic converter
or other related sensors
are causing the fault to come back
if needed .....fit a new air filter...

how the test is determined

P1294-TARGET IDLE NOT REACHED 3.3L/3.8L
When Monitored and Set Condition:
P1294-TARGET IDLE NOT REACHED 3.3L/3.8L
When Monitored: With the engine idling and the transmission in drive, if automatic.
There must not be a MAP sensor trouble code or a Throttle Position Sensor trouble code.
Set Condition: The engine idle is not within 200 rpm above or 100 rpm below the target
idle for 40 seconds. One trip fault.

POSSIBLE CAUSES
INTERMITTENT CONDITION
IAC MOTOR PASSAGES
VACUUM LEAKS
AIR INDUCTION SYSTEM
THROTTLE BODY AND THROTTLE LINKAGE
TEST ACTION APPLICABILITY

ONe of the "easy" fixes is buy a can of throttle body cleaner. Remove the air intake near throttle boddy and clean the inside of throttle body as best you can this should help it. If it doesnt have it checked out it could be more advanced problem. Good Luck.

Sometimes the Computer [PCM] that controls the engine will loose it's memory on how you've driven it when power is removed. It should reset itself after a few miles of driving.

If it has not pulled any codes (idiot light). Clean your throttle body, and change your spark plugs with A/C Delcos #41-103, most other brands will cause rough idle like Autolites and Bosch. This would be a cheap way to fix this problem.

If by chance you have just recently changed the battery or had the battery unhooked. Let me know, it's an easier fix that costs virtually nothing.

I would suggest having the Alternator checked for the proper amp output. Although it may be making enough power to keep the battery charged, it may not be making enough to power the vehicle and still be the reason the engine performs rough at low RPM's under accessory load.

Throttle body needs to be cleaned.

Did you replace the plugs with the same plugs (Manufacturer) as the plugs you had in there. Some cars are very picky with plugs. ie: some Japanese cars will only run well with NGK Spark Plugs. Try to use only what Subaru recommends in your engine for the best performance.