97 lesbare idles and stalls

97 lesbare idles low sometimes and stalls out. hard to start warm or cold. take about 2 seconds to crank. sometimes erratic idle at start up. when idling drops below 700 for very short time then goes back to normal idle has stalled out while after shifting into park and once while turning

I had something similar last year and I knew it was a sensor but had trouble figuring out which one, I thought it might have been my Throttle sensor like posted on another site...turned out it was my Mass Air Flow Sensor - rapping on it (like the repair manual mentioned) didn't tell me anything conclusive but
unplugging it immediately cured the rough idle - it goes into in 'open loop'/default mode if I recall correctly...but fuel consumption will be poor when left like that.
I ended up getting one out of an Olds (Aurora?) from the wreckers and looking inside you could see it was clean...no gunk caked on them inside.