My gauges would jump, then car would just die. No noise, anything. Or would start then just die. It has no spark.

I would try turning the engine, to make sure it's not locked up

check for charge rate , try a jump start

Possibly a fuel supply issue. Will require a fuel pressure tester. Could be in tank pump or a bad fuel pump relay. In a quiet environment, turn key on (not start position ) and listen if you can hear the guel pump run for 1 or 2 seconds.

I would guess your alternator is failing or has failed. Your vehicle will not run if the battery is dead and the alternator has no output.

First you must check to see if engine is mechanical sound by performing a compression test. remove the spark plugs install a compression gauge in the spark plug hole and crank engine about 4 cycles compare readings to all cylinders reading should be around 125-150 psi readings in the 50 psi range possible jumped or broken timing belt. If engine is mechanically sound test for spark at the spark plugs use a spark plug laid against valve cover and have some one crank it over look for the spark to jump the gap. A no spark problem is internal in the distributor.

After starting the vehicle, look at the volt (alternator) gauge while one at a time shutting the radio and A/C off. As the grounded or shorted load is removed, the voltage should restore and show on the gauge.

Alternator.

It sounds like you already solved your problem. Attach fuel gauge to fuel rail pressure line and monitor for fuel pressur (above 30 p.s.i. @ crank). If pressure low suspect pump. If pressure o.k. but dies out and pressure drops but restarts, check oil sending switch as this controls fuel pump. Computer primes pump for start, then oil sender powers up pump for normal operation. Check for oil leaking at terminals on sender. Also check plug connector at fuel sender on tank as they are known to melt and fail. If fuel not problem, check for spark as ignition module failure is common. Have obd2 diagnostic run to check for codes as this may help with diagnosis.

Check the ignition coil packs. It sounds like a spark problem.

problem like this on garden tractor ,was weak coil ,-when engine at low manifold pressure[idle] spark could jump gap and fire cylinder ,higher pressure /under load-wouldn't fire...check color of spark -orange,yellow ,white spark=weak, blue spark is stronge,