Gastroesophageal Reflux Disease (GERD): Given the recent negative upper endoscopy, which rules out ulcers and other mucosal abnormalities, and the difficulty swallowing starchy foods, GERD is a plausible diagnosis. The timing of the pain (around 4 or 5 AM) could be related to nocturnal acid reflux, which is common in GERD. The difficulty with starchy foods might suggest dysphagia, but in the context of GERD, it could be related to esophageal dysmotility or spasm.

Esophageal Dysmotility: This condition could explain the difficulty swallowing certain foods and the severe epigastric pain. Dysmotility disorders can cause chest pain and dysphagia, and the symptoms can be exacerbated at night.
Functional Dyspepsia: Despite the negative endoscopy, functional dyspepsia remains a possibility. It is characterized by recurrent upper abdominal pain or discomfort not exclusively relieved by defecation or associated with a change in stool frequency or form. The early morning pain could be related to increased acid production or other functional disturbances.
Eosinophilic Esophagitis: Although less common, this condition could cause dysphagia, particularly with solid foods like starchy ones, and could potentially cause chest pain. The negative endoscopy might not have identified the characteristic esophageal rings or strictures if they were not present at the time of the procedure.

Acute Coronary Syndrome: It is crucial to consider cardiac causes of chest pain, even if the pain is epigastric and occurs at a consistent time each day. The difficulty swallowing could be unrelated or a manifestation of a more systemic issue.
Esophageal Perforation or Rupture: Although rare and typically associated with more dramatic symptoms, any condition that causes severe chest pain and difficulty swallowing must be considered for perforation or rupture, especially if there's a history of forceful vomiting or other predisposing factors.
Pancreatitis: While the pain pattern is not typical, pancreatitis can cause severe epigastric pain and can be associated with difficulty eating due to pain. The timing of the pain could be related to increased pancreatic enzyme secretion or other factors.

Esophageal Cancer: Although very unlikely given the patient's recent negative endoscopy, esophageal cancer could cause dysphagia and chest pain. However, it would be unusual for cancer to cause such specific timing of pain without other significant symptoms.
Gastric Cancer: Similar to esophageal cancer, gastric cancer is a rare cause of these symptoms, especially with a recent negative endoscopy. However, it remains a consideration in the differential diagnosis due to its potential severity.
Intramural Hematoma of the Esophagus: This is a rare condition that could cause chest pain and dysphagia. It might not have been identified on a standard upper endoscopy if it was not suspected and specifically looked for.