Car not idling and cutting off. on 2000 Lincoln Town Car

My car will crank great somedays and not have any problems. Other days it does not want to start, will not idle properly and will cut off on me. No lights are showing, no codes are coming up on the engine analyzer.

Asked by for the 2000 Lincoln Town Car
Certainly there could be several causes... I'm leaning towards air flow issues. A sticking idle air control valve could cause idle issues, hard start and possible stall cold. Sure, you could have intermittent fuel pump issues, a spark issue...but my hunch is idle air control valve If it is sticking, sometimes you may be able to gently tap on it (top of the intake manifold area under the hood, at the end of the rubber air tube, by the throttle body). Tapping on it may un-stick it for the moment. Does not always work.