This is not an intermittent problem and is present during and after engine warm-up. It is mainly a problem while increasing enginge speed. Load does not seem to be a key factor. Once you get the reves up, it seems to be able to hold a steady speed.
The mechanic changed out the distributor cap and rotor with new ones with no effect. I will check on the plugs but putting new ones in had no effect. How do you distinguish between the platinum plugs and the proper ones?
Thanks for your inputs.