"Yet another GPS module, claims to be more accurate, resistant to noise.
NEO-7P PPP GPS RECEIVER WITH EMI PROTECTION +HMC5983 PRO VERSION
$249
http://www.csgshop.com/product.php?id_product=212"

"Firmware 3.1RC5 seems to have solved the problem. The yaw servo no longer creeps over to one side on the bench and I've got level flight with the props on."

"It creeps on the bench, with props/outside it leans over hard and yaws like crazy the more throttle I add."

"Should I try the latest firmware (RC5)?"

"Yeah, I've tried reversing 4 and 7 and all combination. It'll just cause the servo to creep in the opposite direction. At least that proves it's software...I think."

"Yup, loaded the firmware from the Mission Planner. Tried Stable and one of the Betas - went back to Stable. 
When there are no props installed I see the problem as well but it's really slow. After throttling up the yaw servo will gradually creep off…"

"My APM 2.6 3.01 yaw servo tilts on throttle up. As I throttle up it tilts in proportion to the amount of throttle given. It centers fine when idle, the ranges from the TX all make sense in the mission planner. I've calibrated and re-calibrated a…"