Non-OEM O2 sensors being behind poor performance has come up
here before. I echo Misfit's suggestion.
https://www.automedicsupply.com/ has OEM ones for about $35
total for your 88 CRX. I bought a new OEM O2 sensor here a
few years ago for my 91 Civic. No problems in the
transaction. Works great.

Also, thoroughly purge the cooling system of air. Various
idle control components are cooled by it. Air in it will
cause sub-optimal idling, among other things. Make sure the
fan comes on twice during the purge process. From cold
engine to fan coming on twice may take over 40 minutes. It
does on my 91 Civic.

"djathens" <djathens2@yahoo.com> wrote
>I have an '88 CRX HF with 175,000 miles on it. The engine
>shudders
> pretty violently when the accelerator pedal is held at a
> particular
> spot in its range of travel. It occurs in any gear, at any
> RPM. It is
> more noticeable at lower RPMs probably due to the lower
> inertia of the
> reciprocating mass. If I press the pedal down past this
> point, say
> ~1cm, it goes away. Similarly, if I let up on the pedal
> the same
> distance, the shaking also stops.
>
> Car has new plug wires, new O2 sensor (Bosch), new
> distributor, and a
> MotorVac flush service done. Its also had a new timing
> belt put in and
> a valve adjustment done in the past 25k.I suspect it could
> be the
> throttle position sensor, but I'm not familiar with its
> construction.
> Is it possible that it could have worn out in this spot
> and is sending
> bad/no signals? Any other ideas?
>
> On a related or unrelated note, the car also idles
> erratically,
> sometimes too high (1100RPM), sometimes too low (250RPM),
> sometimes it
> bounces between 900-1100RPM. A Honda tech told me my
> accelerator cable
> was too tight. I haven't fooled with that yet.
>