1994 Toyota Corolla shake at idle

my car shakes when in park and idle but when put in gear the shaking is a little worst. i do notice when i accelerate it will shake a little. at crusing speed the shake is very little. Work done to the car: plugs,wires, cap and rotor, engine mounts, and air filter. what next. what I thought it might be is a Intake manifold gasketght leak? thanks so much for your time.
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