I would have thought your problem was more likely to be with the printer, rather than the computer. Have you tried doing a print head alignment? Or maybe the paper feed is the problem?
I've always had better luck with Canon printers than Epson.
Mac Pro dual-2.4 GHz, 10.13.6, 24 Gb RAM, 250 Gb Samsung EVO SSD/Velocity Solo PCIe card, 2x3Tb Seagate HD, 1x3Tb Hitachi HD, Dell 2408WFP; Canon PIXMA iX6550; CanoScan 8800F; MacBook Air 1.8 Ghz, 8 Gb RAM, 10.14.5, 256 Gb SSD; Vodafone Home Hub/BT Wi-Fi Extender.