Often this problem is caused by worn ignition parts. Your V6 could need new plugs, when were they last replaced? If they have more than 30K miles on them or if they are more than 4 years old the plugs could be the problem. Also your motor has 3 coils that fire 2 plugs each. One coil sits on top of the plug in the front of the motor and it has a plug wire that goes to the rear spark plug. Those 3 wires to the rear plugs need to be replaced, if they are 5 years old they are due.