Why would there be inadequate peristalsis if tests reveal no autoimmune disorder and no strictures or GERD problems?

Ineffective swallows. Esophageal movement disorders are not as well understood as we would like. Many fall into the "unknown cause" category. I would recommend you carefully review with your GI provider the medications you are taking: narcotics, calcium channel blockers and anticholinergic medications can affect esophageal function. Eosinophilic (allergic) esophagitis can be eliminated by mid-esophageal biopsy.