Your 2000 4.8 liter Sierra might run rough at an idle because of clogged fuel injectors or a clogged fuel filter. You might also have gotten water in the gasoline.
check the idle control valve not that hard to replace and inexpensive
What causes a car to idle good and run rough when you give it gas?
Vacuum leek
i think it causes bad/rough idle
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MAF senso, or transmission fluid.
You broke it. Way to go.
check dist. cap for water
There are several things that can cause your 2004 Chevrolet Trailblazer to idle rough. The most common causes are a dirty fuel filter or a dirty air filter.
Why does my 2000 Pontiac Grand Am, with a 2.4L engine, run rough at idle but runs normally when placed in neutral? I changed the plugs and air filter, but the problem continues.
injectors are a common problem
Could be the TPS, it will cause it to idle high and low and make the car become sluggish, but a vehicle will run without one, but it will run very rough.