This usually comes from worn spark plugs; on which the electrodes have become rounded off or the gap has become too wide; often along with spark plug cables which have developed excessive resistance; and a coil, distributor cap and rotor which have lost insulation due to carbon deposits on the inside or dirt on the outside.
I would install a new set of Bosch Super Plus # 7953 spark plugs, at .044" gap, and replace the spark plug wires with a set of mag core wire; either Bosch # 09813, or BWD/Niehoff # CHU606 or CHU606F, or Beck Arnley # 1755980, or Standard Motor Products conductive silicone core wire # 6075. Also get a new Beck Arnley # 1746958 or Bosch # 03329 distributor cap and Beck Arnley # 1737956 or Bosch # 04259 rotor.
Thoroughly clean the outside of the ignition coil tower and nearby surfaces of all dirt and grease. I would also recommend replacing the fuel filter, inspecting and replacing the air filter; if it does not allow light to pass easily through the filter element, and cleaning the mass airflow sensor (using only mass airflow sensor spray) and the throttle body.