The year, make, model and engine info would help but, first you need to determine the cause before you can fix it.
no
change the spark plugs
Check timing. idle could also be set too low (rpms) so vibration is increased.
lower rpms use less gas higher rpms have more power
Both can cause it.
i have audi tt and low rpms the air gets cold but at 2000 rpms it get warm
There could be any number of reasons but it could be the idle is set too low. The idle is the rpms that your engine runs at just sitting there without you stepping on the gas. It should be somewhere between 800 and 1000 rpms.
Its cause you are low on Freon. You need to put some in but when you put it in your car needs to be reved to about 3000 rpms. The reason it doesn't work is because when your idleing you are in low rpms and there isn't alot of pressure in the compressor. But when you do move it kicks on. You will need someone to help you do it but its an easy process.
The engine coolant level is low. Add more and the pump will be able to move coolant at the lower rpms.
If it's cold outside, it's because ECU use ambient temperature sensor and coolant sensor to manage RPMs. After you start the car the coolant temperature is low and ECU sets RPMs very high, when it gets warm RPMs drop down until engine reaches operating temperature.
It's possible that the idle speed is set to high or low. When you shift into drive, power is applied from the motor through the transmission to the CV axles. If the idle is set too high there will be too much power applied to a "stopped" car. If the idle is set too low, then when the car is put into drive, the RPMs will drop and the car will apply more gas to keep the engine from stalling. Start your car and watch your tachometer. It will normally start off high (between 1-2k RPMs) then it should lower within a minute. Note the idle RPM. It should be around 1k RPMs (+/- 300 RPMs). If it's outside of that range or if the needle moves a lot, then there's something wrong. You can find the factory spec idle speed online if you look.
You do not need to modify the alternator if it is working properly. The voltage regulator controls the output of the alternator and it does function at low RPMs, if all systems are working properly. So if it is not charging at low RPMs you have a problem. Most auto parts stores will check your charging system free of charge.You do not need to modify the alternator if it is working properly. The voltage regulator controls the output of the alternator and it does function at low RPMs, if all systems are working properly. So if it is not charging at low RPMs you have a problem. Most auto parts stores will check your charging system free of charge.