Intermittent engine problem

Car runs perfectly and then suddenly.....dead. Engine quits...any speed from idle to 80mph. Tach drops to zero, even with engine turning as car coasts downt he road, but radio and other gauges still work. I can hear a clicking sound coming from the dash (sounds like it's behind the stereo) whenever it kicks off and also when it kicks back on. Sometimes it goes on-of-on in quick succession...each time it does, the tack goes on and off with the clicking as well as the engine.
The obvious answer is a bad ECU, but it has been recently replaced. Anyone else know of anything that can cause this? Is there a circuit breaker built into the ECU that could be kicking in and out causing the clicking sound I hear each time it goes on or off?

Hopeing someone has an idea....intermittent problems are rough to diagnose at the dealer without lots of time and money.

Thanks in advance,

Steve

have you checked your fuel pump?

have you checked your fuel pump?

That wouldn't make the tach go dead while the engine is still turning over from rolling down the road in gear would it? And the clicking sound coming from inside the dash? I really think it sounds electrical...but then again, the whole electrical system isn't dying because the radio and other gauges still work.

MFI relay. Its on the passenger side of the console under the carpeted panel. Thats whats clicking and it could be faulty.

MFI?? what is that? sorry can't figure out the acronym

MFI relay. Its on the passenger side of the console under the carpeted panel. Thats whats clicking and it could be faulty.

I cant remember what it is either but you cant miss it when you pull the passenger side carpeted panel off the console.