Probably has a bad pass side blend door actuator. There is a relearn pricedure for them you may give it a try and get lucky for a while.
One method here- http://www.sparkys-answers.com/2011/08/hvac-actuator-recalibration-procedure.html.
Another method I've had luck with is to start the truck, slowly increease the temp from full cold to fully hot in about four diffrent stops, pasuing momentarly at each stop in the range, letting the actuator catch up. Do that 4x from cold to hot. There is a procedure for this somewher, but I cant find it now.