Bought a 5-speed 96 Geo Tracker with about 75K Miles from a friend.  Replaced the normal stuff; Timing Belt/water pump, spark plugs and wires, fuel filter, air filter, PCV valve, oil and oil filter, A/C clutch relay, front O2 Sensor.  About once or twice a week while the engine is at normal operating temps. the idle just drops down to zero and engine stalls.  Then it's good for a few more days, then it does it again. There is no dieseling, no major shaking, it just drops down to about 200 then it stalls.  While it's running, even when it dies at idle, there is plenty of power, so no loss of power. I have checked the battery terminals for tight fits.  I have been working on this issues for a couple of months now and I am lost at this point. Frustrated, I finally just tightened the accelerator cable, and lubed it, so when this does happen the engine still revs higher and would not die. But, now when the engine runs ok I am idling at 1500 rpm.  I hope it is not a bad keyway on the crank. Any ideas? I greatly appreciate any ideas.  Thanks, Dave