During warm up, sluggish acceleration. Where do I start looking?

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'92 Geo Metro 1.0 L, manual tranny. When the engine is cold, great acceleration, as it starts warming, has a "dead spot" and sluggish acceleration. Once it is up to operating temp, most of the sluggish acceleration goes away, but not always. Have changed fuel filter, new plugs, plug wires, distributor rotor and cap, ran some Seafoam carb/injector cleaner through it, changed the MAP sensor, put on a new O2 sensor. Still doing the same thing. What else can I look at for the problem?