The TBI, albeit unsexy, is an incredibly reliable fuel injection system. I suspect your issues are elsewhere. Are your plugs, wires all good? Any fouling?Have you triple checked your firing order and wire location? I’d also try an OEM coil, they’re cheap on eBay or Amazon. Those street fire coils are garbage in my experience, the Accel ones are even worse. I’d also verify timing, though you said you’ve done that. Valve adjustment could also cause these issues.
You could go aftermarket EFI or put a carb on it, but IMO not worth the cost at all in your application.