What causes a rough idle on a 2002 chevy TB?

Do you have any trouble codes?

check for vacuum leaks!

Here's a link to your code.

My 02 did the same thing. If I were you I'd first check for vacuum leaks and check the intake manifold gasket. They are known to go bad.Take engine cleaner, or brake cleaner and spray directly onto the intake while the engine is running. This is right under the fuel rail. Spray and listen for a change in the idle. If there is any change at all, the intake manifold is bad. Spray all vacuum hoses too. If that is not the problem you should clean the TPS throttle positioning sensor, and the AIC air idle control. Also clean the throttle body. These cars are known for this too.. First take off air cleaner hose, and disconnect the battery. On the throttle body TB you will see 2 10mm bolts. Undo them and the throttle cable. Don't lose the metal gasket. Take TB off and look at the back side of it. Is it carboned up? If so, clean with same cleaner making sure the 2 vacuum hoses are clear. Take the AIC off with a #20 torx screw driver. Dont lose the rubber O Ring. Clean it up, but dont try to move the plunger. Clean inside the TB where this plunger seats. Dirt can cause your symptoms. Clean it up good scrapping the carbon off the back of TB. The TPS is right above the AIC and can also be cleaned up a bit. put it all back together and it should run right.It's usually one or the other with these engines, please let me know what your test results come up with thanks

Check air filter. Check for any vacuum leaks. Check condition of plug wires. Were new plugs pre-gapped? If not, make sure the spark gap is correct for your vehicle.

Many of the 6 cyl. engines are prone to carbon build-up in the throttle body. If this is the case, it is best to clean it off the car and is fairly easy to do. Remove the snorkel, 1 electric fitting on the throttle body (a little tricky) and one vacuum line on tb as well. Four bolts remove the tb from the engine and the throttle body can be cleaned with throttle body cleaner from any auto supply store. An o-ring attaches the tb to the engine so that you will not destroy a gasket during the repair. Pretty easy and should take less than 1 hour, but be careful of sharp edges in the throttle body.

yea id definately try cleaning ur throttle body 1st. My 03 1500hd had the exact same bad idle after my battery went bad it would die at lights unless i kept foot on gas i cleaned throttle body runs perfect now took 30min cost 8$ for cleaner at autozone and theres how to videos on you tube

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.

fuel mix? new fuel filter? throttle body injection? gasket to it OK? (there have been issues). cheaper grade spark plugs? just listing most common causes of rough idle complaint. also try manually cleaning throttle plate and tweaking up throttle angle screw (aka minimum air rate adjustment)

Do you know if the plugs were changed, a bad or broken plug will also cause rough idle and slow acceleration?

unsure if this is petrol or diesel model. check basics first,air filter not clogged,sparkplugs not sooted and gaps burnt wide. if it is a GDI V6 model,thay have common fault with dirty throttle body(TB) and air mass unit,causes rough idle and gets worse over weeks until it doesnt improve.this can be easily fixed by cleaning with solvents available for air flow sensors and tb's. if engine has plastic cover,remove this to access TB