92 Dakota, Runs rough when cold

I have a 92 Dakota with 3.9 and Automatic Transmission. It runs rough when cold, even after I warm up engine for 10 minutes. it seems to run OK for about 1000 feet, then it bucks and kicks and runs very rough and will not rev up. After I travel Two Miles it runs fine. I Have replaced the Wires, Plugs Distributer Cap and Roter, Pcv Valve,EGR Valve in the last 3 months. Last Spring a Mechanic did a Diagnosis, all systems checked. At that time he installed a pick up plate assembly in distributer. Now the problem is back as stated above. This week I had another mechanic do a Diagnosis which showed all systems OK. This mechanic was reluctant to do anymore repair, but did informe me of a bulletin from Oct. 1993 regarding systems of hesitation and rough idle after cold starts. Repair Procedures, Replace Powertrain Control Module. Today I replaced the ECM. Same Problem. Any Suggestions?

Bob