Idle stumble

[nortex]

I just bought a 99 Silverado 1500. Upon startup it stumble before it picks up. If I rev it up to 3-3500 and let it fall it drops to near 0 and comes back up. Before I bought it the guy had the plugs, wires, cap/rotor, fuel filter replaced.

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[kenbronnson73]

Runs smooth just too low?First thing would be the Idle air control.It's job is idle speed.Running rough is a different story.I mean if you hold the pedal at like 5 or 600 rpm is it smooth or no?The IAC may be able to be cleaned too.

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