My 97 4.2 seems to have plenty of power as long as the A/C isn't on. It has more takeoff power and other places where it is weak otherwise. Is there anyway to compensate for the loss of power that the air takes other than the usual general modifications?

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1997 XL,4.2L, modified airbox, K&N filter, aftermarket power windows and door locks, superior chrome spoke wheels, dual outlet muffler with left and right pipes, 84,000 miles, older model Ford rails.