Location of . idle control valve in mazda6 3.0 2004 e 3.0

Clean any black sooty carbon from inside the throttle body bore and plate as well as idle air control valve passageway . The soot restricts air at idle and as soon as you open the throttle by applying the gas pedal it allows enough air to run smoothly .

Hi this sounds like the idle control valve is clogged.

have pressure relief valve checked on low side of a/c pipe

Try cleaning the throttle body and throttle plate. Next is the idle air control passage, pintle and seat. If all that fails, look for vacuum leaks which can be crucial at idle where fuel is light and any leak will cause a lean mixture and stalling, especially with AC on and the vehicle in drive usually.

The idle air control valve (IAC) is designed to increase the idle speed when the AC compressor kicks in to prevent the engine from slowing to stall RPM. It also keeps the engine from run-on or dieseling when the car is shut off.

The emissions controls, vacuum hoses etc are likely blocked up causing a lack of response from the engine when pulled into gear.
Most auto's have an anti stall device. There are several devices that need to be cleaned and or hose checked for blockage or wear/leaks around the engine/trans to determine the fault. Bear in mind this is a 24 year old car and may be just needing a little TLC.

You can in most cases repair this slow speed stall or unstable idle by cleaning the engine throttle valve and the idle speed control valve using a product called CRC Spray Throttle valve cleaner. Spray the cleaner into the air intake of the engine with the hose removed from the throttle body, the engine will try to stall so hold up the idle speed manually. Once you have used up about 1/2 can of the cleaner stall the engine out while spraying and turn the key off, disconnect the negative battery cable for 5 minutes and then reconnect and drive the car for a about 25 miles of varied driving modes. If this doesn't cure the problem you may need the fuel injectors professionally cleaned by the dealer service dept.

I'd start by checking the idle air control valve, google it for your car and it will give you location, unplug it and the car should die, if not good possibility it's bad.

Usually a problem with a dirty throttle body or a faulty idle air control valve. The computer controls idle speed by regulating how much air enters the intake thru the valve.

Possible dirty throttle valve and idle speed control valve.

Throttle Body Cleaning on vehicles without electronic throttle control (most 2003 and down)

You can in most cases repair this slow speed stall or unstable idle by cleaning the engine throttle valve and the idle speed control valve using a product called CRC Spray Throttle valve cleaner. Spray the cleaner into the air intake of the engine with the hose removed from the throttle body, the engine will try to stall so hold up the idle speed manually. Once you have used up about 1/2 can of the cleaner stall the engine out while spraying and turn the key off, disconnect the negative battery cable for 5 minutes and then reconnect and drive the car for a about 25 miles of varied driving modes. If this doesn't cure the problem you may need the fuel injectors professionally cleaned by the dealer service dept.

Try to clean the throttle plate with a tooth brush and B-12 chemtool (parts store will have). Engine off / remove air inlet duct, open throttle, spray a little and clean thoroughly.