Man! I wish I'd seen this post when you had the problem to begin with. I had the same problem around that milage. Do you want to know what it is?
Coil pack.
I brought my car to the stealership, and they said it was either bad plugs/wires, or coild pack. Once the plugs/wires are replaced if it continues then it's a bad coil pack. I repalced the plus/wires, and no, they are really hard to do on the V6. It's sure a pain in the keister. Well, after the plugs/wires were replaced, it continuted. Then I replaced the coil pack, and bam! Fixed problem.
My car is at 175,000 miles later and she is still kicking. Since then I have had the spark plugs/wires replaced. Basic maintenance.
Good luck. Let me know what you find out.
