I had Issues like what you are discribing here!! Make sure to check all the boost lines for tears in the couplings and that the couplings are properly fit, especially to the inter-cooler!! I went to the use of T-Clamps instead of the stock worm clamps. The stock clamps, when over tightened, may cut into the rubber couplings causing leaks!! Boost leaks may throw codes so if you have a Service Engine light lit get it checked. If you are running too rich the computer will throw codes as well. Also, the stock BOV only hold about 24psi. From My experence you shouldn't get any flutter from a stock BOV unless you are trying to push more than 24psi by means for a boost controller. (goes for both manual and electronic)