wont idle

I'm having a problem with my '91.

It suddenly wont idle this morning. I can get it started, and can keep it going if I keep pressure on the gas, but as soon as I remove my foot from the gas it dies.
I checked the engine and there is some slack in the cable going to the throttle... but I couldnt see any way to adjust it.
As it was pouring down rain at the time (and still is), I couldnt really spend alot of time fishing around looking for additional problems....
I did notice that there was a 'clicking' sound coming from somewhere around the battery when I wiggled the cable.

any suggestions on where to start?

I had an 89 that did the same thing, only during and after a rain......it was the plug wires on mine.....even tho you may not see a crack, theres could be a lot of mico cracks in the wires......does it run fine when it s dry out? if so....id def check the wires....that clicking you heard could be the wires cross-firing, also do to bad wires....just my 2 pennies tho....im sure as hell not a machanic.......worked on mine tho......