Originally Posted by ChrisWorrell
The underdrive pulleys are actually hurting your ability to power your car. The idea behind underdrive pulleys is that it slows down the rotation of the belt, therefor the alternator pulley does not spin as much as it used to. This causes less power to be regained through the laternator then usual.
This could be some of your troubles since you have underdrive pulleys
Alot of people here have underdrive pullies and they dont have the same problem. Most underdrive pully kits like the one from UUC dont come with alternator pullies, so u stick with the stock one most of the time.