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It sounds like the symptoms of a timing belt out of time by a tooth or
two. The timing belt is at the opposite end of the (cam) shaft that the
distributor is driven by. Doubtful the tech would have had the timing
belt cover off. You didn't mention your mileage or whether you've had
the TB replacd recently. (doubtful you needed the distributor)

Full-speed problems will happen for a plugged fuel filter, but it should
be predictable. Into a headwind should make it worse, or climbing a hill
at speed.

I'd run a tankfull of gasohol through it to see if you've got plugged /
leaking injectors, just because it's a wonderfully cheap experiment.
Check all your fluid levels, and air filter, per the owner's manual.

'Curly'

I'm no expert, but in addition to what Curly said, for my 1991 Civic at the
first sign of running rough, I'm replacing the oxygen sensor. (Probably gonna do
it anyway as a pre-emptive measure. I'm told O2 sensors gradually deteriorate in
performance, as opposed to just all of a sudden giving up the ghost.)

Best prices I've found for what appear to be OEM oxygen sensors (for my car
anyway):
https://www.automedicsupply.com/

Thank you both for your responses. I had the shop replace the oxogen sensor
during the tune-up, but did have a problem with too low of an idle after
the tune-up. He adjusted it, but it still seems a bit low. The shop is
going to adjust the timing today.  I'll see if that solves the problem.
Thanks again!!!