newbie - engine shudders and shakes at startup

[stillkickin]

On 89 turbo 2.5 Caravan ... Upon startup you can watch the tach adjust around a bit for about 6 seconds and then she idles fine once the tach makes its final move. Upon restart later it may do the same thing, or, the symptom may be more brief or non-existent. No codes...copper autolite oem plugs are 2,000 miles. I have changed ecm boards w/no change. Sensors? Replace plugs anyway/brand? All ideas appreciated...thanks

[dodgeman87]

Inside the distributor and underneath the Hep there is a metal wheel with plastic rivets, sometimes those plastic rivets start to break apart and cause problems.