With a volt meter, cehck the coil voltage with and without the engine
running.
Running: 8-10 volts or so.
Off: 12 volts or so.
During cranking the voltage will be high but once it starts, the ballast
rsistor will keep the voltage down to avoid baking a coil. If a coil does
get damaged, the output can drop a lot due to damaged windings inside.
Replacing a coil is one option, but I'd check to see you are getting the
proper voltage to begin with. Don't be alarmed to see 8 volts while
running- that's nomral.
Of course, a bad alternator/voltage regulator that is keeping the entire
electrical system low will cause similar problems. My 94 Astro minivan
just ate an alternator and when the battery dropped to 10 volts while
driving, the vehicle refused to speed up- engine would flatline really low
in the RPM range.
-Vegaman Dan
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