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Mercury Monteray 2004 model

My mercury Monteray 2004 model, suddenly loses power while driving. This has happened both on the freeway and on the local roads. I then have some how driven it to the shoulder. After stopping for couple of minutes when I restart the car it works and I have been able to drive it. I have taken it 3 times to the dealer and he has not been able to identify the problem. I am extremely scared of driving the vehicle. We even had flight recorder from the dealer on the vehicle and recorded the incident 3 to 4 times and still the dealer has not been able to figure out what the issue is. They say that they have tried several times and have not been able to recreate the issue. They say that they have tried to recreate the issue with a computer attached so they can record the issue when it occurs. But apparently they have never been able to recreate the issue. Other wise the van is in excellent condition. Can you suggest what could be the issue? We have not been able to use the van for over 6 months and do not know what to do with it.

Please suggest what can help me diagnose the problem. Appreciate your help.

Lilly

I would look at fuel pressure. Fuel pumps can be intermittent.

checked fuel pressure and that seems to be ok.

Try another shop. Properly set up, an event recorder should be able to monitor fuel pressure, ignition, and other critical events such that a shop can look at the traces, corrolate the readings with the event, and determine the root cause form there. For example, if a fuel pressure drope precedes a drop in rpm, yet no anomolies appear on the ignition pulse trace, the problem is fuel supply. If the fuel supply remains constant while the ignition pulses become erratic, it’s ignition related. One should even be able to read the traces from the various sensors.

Come to think of it, did they test the crank position sensor?