1991 Buick Lesabre

On this vehicle if you lightly tap on it with something like a tire gauge or small screwdriver with the engine running at idle; you will hear the engine stumble if its bad. The only other way I know of is look at it with a scan tool to see if its in its proper parameters.
BILLybob

Like many other things it will also have your car shutting off while driving, or right when you lightly pres the gas. Also from what I remember, your car wont accellerate perfectly all the time, sometimes youll have to let go of the gas and press over until it gets the kick. Also your car may struggle to go when at low speed(stops and goes)