2000 hyundai sonata 4 cylinder when start up and it stalls won't idle start again and stalls if i step hold gas pedal will runs keep revs and almost dies then back rev and almost dies again then let go pedal it dies there no check engine light

Check fuel pressure. If low, change fuel filter. If good, check valve timing.

Hyundai Elantra Questions - Engine stalls / hesitations at ...

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CarGurusApr 20, 2013 - Engine stalls / hesitations at idle and low acceleration - Model: 1999 Hyundai ... stopped... and then at one last desperate pump of the gas pedal, the ...Despite all this, most of the time, the car runs smoothly, and several shops have .....Keep in mind that my car is Elantra 2001 with 82k miles on it, the car will ...

My car keeps shutting off when idle.. - CarGurus

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CarGurusFeb 15, 2013 - whenever im on breaks or, it stutters for then cranks right back up. ... of your question, the stalling, hopefully somebody will come by to help you on that. ....Car having trouble starting,rough idling,shutting off at stop 2 answers.

How to Fix a Car That Stalls: 7 Steps (with Pictures) - wikiHow

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wikiHowThere are many things that could cause a car to stall. ... Your engine stops runningbecause it is not igniting gas in the cylinders, this occurs either because there ...

water in gas,use drygas

Sounds like a coolant sensor problem. It signals the ECU for open loop, cold start rich, high idle, until warm up is reached.

could be a few things the start up could be the idle air control sensor (my first thought), the coolant temp sensor for the computer might be a secondary thought for the engine being cold if the computer thinks its warm. that would be the first 2 places i would start without a check engine light or code to reference

Have the idle bypass valve checked, also called idle air control valve.
If that valve is stuck in the closed position, it's not allowing the fuel to bypass the throttle plate to keep it idling, resulting in stalling, but will keep engine running if the pedal is pushed down.

It is possible that when fueling, the fuel is aerated and the pump pulls agitated fuel into the system. you can thry this, fuel up as normal, but wait five or more minutes before starting. see what happens. good luck

Check your idle control valve...

Ok Slow deceleration rev responce was part of the ECU software to keep the emissions down ,however if this has only just started you can try to reset the IAC valve ,the procedure is as follows.

Turn ignition key on ,unplug the IAC valve ,turn the key off ,replug the IAC valve. do this 3-4 times .Then start the engine while holding the gas pedal to 2000 rpm ,then slowley let the go of the gas pedal till the engine idles .

The IAC valve is located on the throtle body and has 4 wires to it.

Sometimes the throtle body needs to be cleaned and then reset.

your on the right route but also check egr valve