My Epson 837 drops both small and large spots of ink mostly black.

My Epson 837 drops both small and large spots of ink mostly black on anything I print from simple letters to ultra premium photo glossy and or matte. I've tried cleaning the heads and blowing out the ink with compressed air and with a clear tube. Ive replaced the ink many times. I only use true epson ink. Nothing compatible. What else can I do? My email is mm3897@aol.com and my name is Mario. Thank you for any help you can provide.