Rough idle

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Six cylinder two wheel drive 92,000 miles.

Recently the check engine light came on. I took the vehicle to the shop and they said they needed to change the fan clutch and gas sensor sending unit for the gas pedal. When the light was on, the engine was running rough when in drive. Once I received the vehicle back, the check engine light was off but the rough idle was still there. I took it back to the garage and now they are saying that the water pump needs to be replaced due to the bearing being bad. The water pump is not leaking at all.
My question is, can a worn water pump cause rough idling? They said they checked the engine on the computer and the engine is not missing. Help!

Engine idle is somewhat rough. Ehen A/C is turned on the engine will shut off. Replaced coil and plug on cylinder six based off misfire code.

My vehicle has an issue with the idle and taking off. At times the idle will be at 900 which I have been told is normal. While idling at this rpm everything is fine. At other times it will drop down to 600 and wants to stall. When you give it gas it bogs down and tends to stall. Also, when the idle is this low it also hesitates on take offs. I am also getting a lean engine code. I have changed the intake gasket, cleaned the throttle body, changed the O2 sensor, MAP sensor, cleaned mass air flow sensor and also added fuel injector cleaner to my fuel. Would the secondary air intake cause this problem or is there anything else I can check?

I have the same problem with my 2005 Trailblazer. Is the Idle Air Control Valve the problem? Could it be the coil(I was told it is a common problem) or even the fuel filter?

When A/C is on idle is below 1,000 rpm and stumbles like it is going to stall out. Does this year have an idle air control and could that be the problem?

Check for any vacuum leaks first. Then check air filter. It sounds more like it is having a hard time keeping up. I do not think it is any switches. When was the last time you did a tune up? Any check engine lights come on?

My vehicle is idling rough. I did a tune up and even had my fuel system cleaned with the three step process at Tires Plus. It is still doing the same thing. Yes my engine light comes on for a day and goes off for a few days and then comes back on and goes off in the same manner. I was told that my catalytic converter is bad. I had an after market catalytic converter put on at the beginning of the year though. And as I was driving last night my lights began flickering and my battery needle was moving up and down every time the lights flicked. What could the problem be? I have done a lot of traveling and I have 144,000 miles on my vehicle. This did not start until about three trips to Texas and back from Georgia.

Hello, I have the EXT model. No work done to motor other than oil changes. Engine idles very rough when cold, even stalls occasionally, but after a couple minutes of driving (when warmed up) it runs just fine. Is this a sensor problem, and if so, which?

Thanks for your blazingly quick response. I did a check on the IAC and learned that 2004 is the first year Chevrolet assembled it with the entire throttle body so it is no longer a separate component. I can see it visually on top there but don't see a way to clean it. Any suggestions?

Also, on the coolant temperature sensor. Where is it located exactly?

It has a rough idle when I start it and leave running for a minute. When I drive about fifty mph it acts like it is losing power. Not sure what is wrong.

I changed the plugs and fuel filter with no change. I took to AutoZone they hooked up diagnostic machine and it said mass air sensor was bad, but my vehicle is not equipped with a mass air sensor. What should I try next it idles rough and has no power when you push on gas.