Overheating ? - Check radiator for water and coolant, and engine for enough oil and not old burnt oil
Often a knock when cold is caused by piston slap, which is pistons rocking in the cylinders until they expand in size when the engine warms up.
Does it quit shaking when it warms up? What engine and year of Aerostar?
The preheater warms up the engine so it will start easier and in freezing weather will help to avoid freezing of the coolant.
Check for vacuum leaks.
If its coming from your engine, you may need a valve adjustment..
cracked heads or block
because the engine is cold. after it warms up the light goes off. Cute! But what causes the blue light to come back on even after you've been driving for a while?
A cold engine will often experience trembles due to the inefficiency of engines when not at operating temperatures. This quickly goes away as the engine warms up.
i have a 2000 dodge work van 318 engine when i start in the morning it stalls several times until it warms up then ok
Valves tapping?
Checl your manual for a cold start injector. if it has one check your voltage after it warms up. if you have voltage after car warms up you have a problem with the circuit. if you don't have voltage, remove and plug the fuel line to this solinoid, start and run car and check your symptoms again.
It is because of how fast the car idles. When you start the car it is idling high and when the engine warms up it slows the idle to about 650 RPMs and the torque converter in your transmission is slipping and not moving you forward at that low an RPM. what causes the torque converter to slip? CAn it be a sensor problem?