more belt woes, and my car doesnt need air, there must be a leak in air intake Options

[opera guy]

I got belt from my FLAPS, finally figured out how to move the alternator to tighten the belt. however, the blet still flaps a lot and eventually will fall off. the belt appears to be chewed up, i dunno why. i dont see a way of checking if the fan and alternator pulleys are aligned correctly w/o pulling the motor.

also, with or without the belt on, my car idles really weirdly. it revs and revs from flat line (almost stalling) to about 1300 rpm. just this constant up, down, up, down...etc between flatline and 1300. there is a distinct continus HISS (is this normal for 914's?) if i cover the inlet for the airbox.. the car idles at about 1100rmp, HISS still present, but no "up-down-up-down..." revving. what am i misssing here.

btw, no mods to air intake, stock airbox with regular airfilter element.

[opera guy]

Its a 1973 2.0. dunno if its L jet or D jet. i'll hve to look up how to tell the difference between the two. thanks for the tip regarding the garden hose. was gonna try blowing cigarette smoke in there but this is probably a healthier idea.