You've probably got a shorted voltage regulator (inside the alternator) that's allowing the rotor field current to go full-on. Put a voltmeter to the battery posts and have a helper accelerate the engine speed (gently). If the voltage goes above 15, replace the alternator. Don't delay- - - -more blown bulbs and damage to the battery from overcharging are coming- - - -soon! I've seen alternators spike voltage into the 30's and above under similar circumstances.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!