1990 Camry D 4 Cylinder 2.0 113K Miles: ECU Question

Ok so after two months of issues, my mechanic was able to determine that my drivablity issues were the result of a failing Mass Airflow sensor and Throttle Position Sensor. When he replaced those, the car drives fine, but I still have the hard start issues after having sat for longer than 3 hours. I put the key in, turn, , she starts. Then dies. Usually she will start on the second try. He then realized that something wasn't triggering the fuel pump to prime. So he changed out the Main Relay. And nothing. So we have determined that they ECU is going bad and more than likely needs to be replaced. Something that costs money. Money I'm going to have to save. My question is. If they starting thing is the only issue that I'm having in regards tot he ECU. And she drives like a top. Do I need to be in a huge honkin' hurry to replace the ECU. Or can I take my time and save up the funds. Or could it not be the ECU and we could be missing something.