Car has rough idle & acceler. then smooths out. Chged plugs, wires & added Lucas

Check engine light on? If so, find out what the fault codes are. If misfire codes, could be an ignition coil. did you use the correct spark plugs? You could check for build up in the throttle body.

It sounds like a problem I recently resolved. My fix was replacing the rubber intake coupling GM part no. 12555840 the repair took me just over an hour. Now its smooth sailing.