93 626 has pulsing idle in "D" when warm

I have a 1993 Mazda 626 with the 2.5l engine and automatic transmission.

When it's warm and I pull up to a red light, the idle seems to pulse at
about 1 second intervals. The tachometer is steady around 700rpm.

Basically is sounds like it wants to run rough, then speeds up just enough
to cancel that out, then settles down and goes back to wanting to run rough
again - at one second intervals.

Maintenance that I've done in the last six months (unrelated to this issue)
are:
- New plugs - gapped
- New wires
- New cap and rotor
- New PCV valve
- New air cleaner
- New fuel filter
- New timing belt and hydraulic tensioner
- New valve cover gaskets
- 2 bottles (at least) of injector cleaner
- New waterpump
- Flushed cooling system + water wetter
- Oil change
- Trans fluid change.

Any idea what it could be?

Noozer wrote:
> I have a 1993 Mazda 626 with the 2.5l engine and automatic transmission.
>
> When it's warm and I pull up to a red light, the idle seems to pulse at
> about 1 second intervals. The tachometer is steady around 700rpm.
>
> Basically is sounds like it wants to run rough, then speeds up just enough
> to cancel that out, then settles down and goes back to wanting to run rough
> again - at one second intervals.
>
> Maintenance that I've done in the last six months (unrelated to this issue)
> are:
> - New plugs - gapped
> - New wires
> - New cap and rotor
> - New PCV valve
> - New air cleaner
> - New fuel filter
> - New timing belt and hydraulic tensioner
> - New valve cover gaskets
> - 2 bottles (at least) of injector cleaner
> - New waterpump
> - Flushed cooling system + water wetter
> - Oil change
> - Trans fluid change.
>
> Any idea what it could be?
>
>
Oxygen sensor