1990 Honda CRX Dual problem

My 1990 CRX HF stalls on me every now and then. Sometimes completely and I have to pull over, sometimes I lose power, but if I downshift and engine revs then it starts right up again. Very unpredictable and frustrating. My mechanic FINALLY diagnosed that it needed a new distributor. They replaced and it drove fine for 3 days. Then the EXACT SAME problem again, but when it stalled completely, I would have to wait (or try many times) before it would start again and (hopefully) run. I took it back assuming they incorrectly diagnosed the problem. They tested for a week and came back with "it needs a replacement ECM." They said the two showed the same symptoms, but that both were the cause. What are the odds both were bad and caused the same problem versus they misdiagnosed the first time and don't want to admit it? Thanks!