low rpm miss

[cloudshe]

1995 55k mi zr-1 engine (perf chip) slight stumble. i've never had anything but smooth strong power since i bought the car, throughout the rpm/speed/throttle range. just recently it has a slight miss just when adding a little bit of gas pedal, around 2000 rpm. doesn't matter much what speed or gear, just happens when running steady state and then slightly increasing pedal pressure, seems a little worse after a few miles driving. no problems at all other modes, full throttle, half throttle, any rpm, valet mode on or off.

where to start? plugs, wires, injectors? do i need a code reader? i want the car to run perfectly when i sell it, i'm just not using it since i retired & main job now is driving wifey around in her sedan or suv. also, i'm working on restoring my dream mid-year

Thanks!!!