This article is from the Chrysler-Plymouth-Dodge FAQ, by Dr. David Zatz with numerous contributions by others.
Cold engine knock a few seconds after startup, lasting about 3-5 minutes
most noticable at 2,000 - 2,500 rpm. Sounds like valve lifter or
tappet noise. Noise loudest when weather colder. Usually disappears when
the car is warm.
Cold idle rough util coolant reaches 50-60 degrees F.
TSB 09-06-93 provides for replacement of the computer.