Dodge Repair: occasional hesitation, spark plugs, split second

Question
1998 caravan 92,000 miles has a hesitation.  no codes come up.  Had engine cleaned and a tune up.  Keeps getting more common.  Does it only for a split second then 3/4 of mile up the road it does it again.  Cannot fiquire it out.  Does it when it starts to get warm and continues.  I do have a pinging noise in one of the cylinders even when I change the oil.

Answer
due to the complexity of your problem a acurate diagnosis is extremely hard, a few suggestions would be the ignition module, cap rotor, wires. remove the spark plugs and check for damage use a magnet with extension to feel down into the cylinders for debris... if this remains a problem take it to a local mechanic..  joe