At 150K miles you should have a very healthy van that will need some TLC very soon. Mine is 237K miles and still strong. My advantage is that I do maintenance myself, keeping the overall cost of repairs to a minimum.
There is a very good article in the web for troubleshooting the distributor. Search for “Power Transistor Test and Ignition Coil Test 3.3L Nissan”. The web site is “www.easyautodiagnostics.com” Your mechanic can use it to confirm the distributor failure.
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