u have a cylnder low on compresson
Wait until it warms up and melts
bypass the the line that runs into the radiator. witch is a trans oil warmer. reconnect both lines together
It will until the coolant warms up.
If sit has a carb. perhaps choke is not releasing fast enough - causing it to run too rich until warm up
try 92 octane or higher.
I have 1998 a Lincoln town car with the same problem.. It idles rough when you start, then smooths out once it warms up and you give it gas. From what I am reading its either an oxygen sensor or you have vacume leak in one of your hoses by the manifold.
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.
replace your mapp sensor
this is caused from piston to cyl wall clearance when engine warms up the pistons exspand and the noise is less. DON'T WORRY ABOUT IT
This is most likely a cold air idle valve which is stuck closed. This is located on the throttle body. You could take it off, clean it and reassemble it, or just pull one out of the junk yard, they usually don't go bad until 200000+ miles.
Possible dirty fuel injectors or TPS sensor.