Changes in play that lead to downswings

[mattgoody]

It seems to me that every time i play poker for a significant amount of time, i always hit a wall, stop winning, and start losing. Right now im playing 25c NL on Full Tilt. I am trying to figure out what im doing differently, but all my major stats (VPIP, Preflop Raise%, and AF) stay pretty much constant. I was wondering if there is anyway to see why im having this downswing. Oh and im using the Poker EV program and i made sure im not losing becuz of a bad run of cards. Im just curious if there are any stats to look at that i might not be finding which could help me plug some leaks.

Thanx,
-Matt