One thing to check: When you're standing and in the drops, you can put a lot of weight on the front wheel. If the tire pressure is a bit low, it can make handling pretty squirrelly as you rock back and forth pedaling. For me with my setup, 100 psi is good and 90 gets squirrelly. The actual pressure for you is going to depend on your weight, steering geometry of the bike, tire/size, etc. Bikes with quick steering are more affected.