help me figure out this miss fire, PLEASE.

Had lots of vehicles but never one that runs like this. It is a 94 Chevy tracker. 4cyl 16 valve multiport injection engine. It will not hold a constant speed without a miss fire. 30 mph or 50 mph on a flat
road it will sound like it has dropped a cylinder. Engine starts easy, without hardly even cranking. Idles smooth as silk. Accelerates without hesitation and pulls strong all the way to redline without a miss. I have changed plugs, cap, wires, and rotor because it sounds like an ignition miss. This made no change. I have seafoamed and ran techtron though the tank this made no difference. Seems low load, light throttle should be when the engine is working the least. I can't figure why this one doesn't like to run there. FWIW I get no SES light, no smoke, no fluid usage. Anyone ever had an engine behave like this? Thanks
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Disconnect the EGR valve, if the miss goes away, you know which area to focus on.
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Have you checked the Throttle Position Sensor? I had a truck years ago that would run quite rough at just above idle. Turned out to be a dead spot in the TPS causing the computer to go crazy trying to tune the engine parameters for a throttle position (voltage) that was bouncing around. Engine would idle fine, accelerate fine and run at a faster RPM fine.

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