My truck takes so long to come off fast idle and somed time it speeds up as you are coming to a stop

Sounds like the idle speed of your car is too low, then the alternator cannot produce enough voltage for any electrical devices. When idle speed is normal or much higher, power will return to normal very fast. It may be that the idle air control valve is dirty or defective.

look on the inside of your wheals and see if you do not have a leaking wheal cereal

Get car on a scanner to check codes.
May have a vacuum leak or inlet man gasket fault

It depends on how fast you are going when you come to a stop.
If you are above 45 mph it could be the torque converter not releasing. If you are under 40mph it could be a faulty idle air control valve or a dirty throttle body. The computer controls idle speed by how much air enters the throttle body thru the control valve.

Hi Jason, I suggest you take the vehicle and have a diagnostic scan carried out. Doing that will pin point the problem area and take out the guess work. I have known occasions when someone has tried to adjust the throttle butterfly, hoping to reduce the idling speed and by doing that have taken the TPS (Throttle Position Sensor) out of the correct adjustment, causing abnormal idle speed. Regards John

Check the base plate gasket under the throttle body, some time the gasket start to leak, and will cause a high idle, if possible with engine running get some water and pore it at the base of the throttle bode, you will hear a suction sound, that's the gasket, replace it.

It is either the Idle Control Solenoid is bad or you need some expert to take a look and increase the idling that is rpm of the vehicle to about 700rpm.

Please do this fast or you might have your vehicle stopping at every red kight.

Good luck and remember to rate this solution.

Cheers.

Three things to check for:

1) High idle switch is on..*(vehicle thinks AC is running but it isn't.
You can try turning on the AC and see if the engine slows down to confirm this one.

2) Sticking or worn out Idle Air Control or IAC, You might get a check engine light with this one.....you might not if it's a mechanical failure.

3) Simplest of all. A vacuum leak. You can get the engine vacuum read while running if you go to a mechanic with a vacuum guage or an OBD 2 ecu code reader. There should be specs on what vacuum levels are normal for you car at idle.

Good luck and be careful!

I've got Hyundai Lantra 1.6 year 2000. It's take time to start when it's hot. When I start my car it revs at about 2k-3k rpm. It also does it when I come to a stop. When I come to a stop it will stay at a higher rpm than that of idle speed. It drives ok when on freeway but uses more petrol. I have changed the water & petrol pump but no luck

If you can keep the engine running with your foot on the gas at a stop it is likely to be the Idle control valve. Older Hondas' have 2 valves. fast idle control (which is prone to cause fast, or surging idle due to vacuum leakage) and the Idle control that takes over from the cold idle control once warmed up. They are located at the throttle butterfly assembly.