I replaced iac sensor and it still shows bad.

What is year--make--model? Any applicable trouble codes? So your having trouble with idle? Remove throttle body, clean throttle bore and any small passages. Check and clean anything that has to do with idle air system.

Problem with IAC - idle air control motor . Or sticking throttle plate in the throttle body , gummed up .
Idle Air Control Valve
How to Clean Throttle Body and Idle Air Control IAC Valve Quick and Easy

Is the check engine light lit ?

05 Chevy Cavalier IAC Idle Air Control Valve Replacement

Bad MAP sensor , your best bet , take to a qualified repair shop .

Airflow meter butterfly covered in carbon and oil remove and clean with carbon cleaner

TRY AND SCAN CAR SHOULD CODE OUT IAC SESOR( IDLE AIR CONTROLL).IF NO CODE PRESENT ITS A BAD IAC.MOTOR OR ITS CARBONED UP .REMOVE AND CLEAN WITH CARB CLEANER IN INTAKE WHERE IAC MOTOR BOLTS TO ALSO MAKE SURE CANNON PLUG AND WIRES ARE IN GOOD CONDITION.AUTO PARTS STORE WILL SCAN CAR AND TEST LAC MOTOR AUTOZONE ECT. GOOD LUCK. B.HARRIS A.S.E. CIRTIFIED 25YR. EXP.

Your problem seems to be the I.A.C. (Idle Air Control) motor. Located on the side of the throttle body assembly, this part is responsible for maintaining proper idle speed when the vehicle is idling. But before you start throwing in a new part, try cleaning the I.A.C. port first. Remove the 2 mounting screws holding the I.A.C. motor. Using intake cleaner spray (not carb cleaner), spray the tip of the I.A.C. motor to remove any deposits, wipe clean. Do the same for the "hole" that the part came out of; use a Q-tip to get in deeper into the port. Get as much of the crud off as possible. Allow excess cleaner to evaporate before starting the engine.

I hope this helps...

Have a great day!!!

The problem you describe could be result of a few different things; however, I would first check your vehicle's Idle Air Control (IAC) sensor/motor. This sensor/motor is located on your vehicles, throttle body and is easy to access. The purpose of this sensor is to control the car's idle under various operating conditions including ambient temperature. In order for it to function correctly, the internal components must be clean (meaning, little or no carbon build up) and it must be undamaged. Sometimes the IAC can be cleaned; however, if this cleaning procedure is not properly done, the IAC can become damaged. This sensor is also sometimes called the "Cold Start" sensor. A new IAC will cost $50-$100. My guess is your IAC needs to be cleaned or replaced. Good Luck!

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The problem you describe could be result of a few different things; however, I would first check your vehicle's Idle Air Control (IAC) sensor/motor. This sensor/motor is located on your vehicles, throttle body and is easy to access. The purpose of this sensor is to control the car's idle under various operating conditions including ambient temperature. In order for it to function correctly, the internal components must be clean (meaning, little or no carbon build up) and it must be undamaged. Sometimes the IAC can be cleaned; however, if this cleaning procedure is not properly done, the IAC can become damaged. This sensor is also sometimes called the "Cold Start" sensor. A new IAC will cost $50-$100. My guess is your IAC needs to be cleaned or replaced. Good Luck!

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I doupt it's the cam sensor. they don't work that way. I would check the EGR (exhaust gas recirculation) valve and the IAC ( idle air control) motor. Both of these will cause a large vacuum leak and make your lope. you can try uplugging them , then plug them back in to see if this makes them work. happens sometimes, bad connection. If that doesn't work I would remove them and clean them first, move the plunger in them. they get stuck sometimes. when you have off you can plug the holes on the engine and start it. see if that gets rid of your problem. I would start with the IAC motor first. The IAC motor is located on or near the throttle body. The EGR is on the intake and will have a flex tube running to the exhaust manifold.

Intake gaskets will **** air when cold and cooler weather causing a skip when first start up. this sounds like your problem

i would check your idle air control valve. And you might want to take a look at your fuel injectors/ fuel filter. To check the IAC motor remove the unit, with the wires connected turn the key to the "on" position without starting the engine, the IAC should move in or out. If the IAC motor does nothing it has probably failed, replace it with a new unit and recheck system. Note: while the IAC motor is removed clean (use aerosol carburetor cleaner) the passages the IAC uses to control idle air speed.