As others have also said, it is highly unlikely to be the ECU, and if you have the urge to replace it for whatever reason, get one from ebay, I dont think this is the problem. OVP relays dont blow at the rate you are talking about, the antilock brake light can come on for various reasons, one of them is an abnormal voltage from the alternator, but the problem cannot be fixed by changing the OVP, it is in the alternator or the voltage regulator, which you have already changed. Measure the voltage at the battery when the car is idling, it should be no higher than about 14V. If the car idles fine and it is shutting off when you depress the pedal, it could be a vaccum leak also. Check vaccum at idle, it should be 20 (I am not absolutely sure but can check) or so at idle and then drops when you depress the pedal. If the vaccum is low at idle, the problem is either a leak in the vaccum lines OR a clogged exhaust system. Without descent levels of vaccum, nothing will function right including the throttle mechanism (i.e. your gas pedal). The catalytic converter will be the first place that such clog will develop in the exhaust system. If you are a person who knows little about the operations of the fuel system in this car, I would take it to the dealer atleast for diagnostics.

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Saumil S. Patel