97 legacy Outback, twin cam 2.5

recently swapped an engine into said car,

Got it running, ran like a sewing machine sounded beautiful all of the sudden I heard a sizzling and the engine slowly stopped and won’t restart.

no spark, but I have fuel and I believe the injectors are firing, I have a bunch of spare parts laying around that are known good so so I started changing them out one by one, including coil pack, igniter, plug wires I did a visual on the ecu no burn marks.

im at a loss I heard the noise that something burned up but no smoke and to visual indicators my next step will be to remove the intake to see if anything under it got pinched but i figured I’d see if anyone else has had a similar situation first before I start tearing things off

 I heard a sizzling and the engine slowly stopped?

Like wires shorting out?

Slowly stopped?  RPM dropped but it was still going?

Have you checked for Spark?  Put an extra plug in, ground it and turn it over.  Nice strong blue spark?

If so, add a small amount of fuel into the intake throttle body.  Does it start and run for a bit?

Is it cranking over normally?

What prompted the engine change?

Did you do the timing belt or any other maintenance on the engine before the installation?

Have you checked the timing belt to make sure it’s not broken?