Car is idling low at about 400RPM , idle was reset at the Mazda dealer last year , said the throttle position sensor was reset ,I played with to no avail , is it done though the computer ?seems to run fine otherwise . Any tips/tricks appreciated.

 

I can't claim to know too much about these cars, but since it is an OBDI system, would thinkthe idle is controlled by the ECU. You might also have a throttle position sensor going bad, or out of adjustment.
On the other hand, you would have a cable operatedTB, so perhaps you could fool it by tightening up on the cable a bit? I don't know if that's a good idea or not, only that I did just that to a Mitsu I once owned w/a low idle.