any ford dealer techs out there

need help diagnosing my wife's 2006 mustang 4.0 v-6 . intermitantly surging or running rough at idle sometimes stalling when at idle , or coasting. has set code p061b ford dealer flashed pcm with latest update but still acting up, they think it may be the mass-airflow sensor. I thought maybe egr valve. anyone have this code set before?