Ok, I have the same car with a similar problem. It is solved by any or all of the following
1) Turning off the A/C
2) Pulling the choke out for a couple of seconds then pushing it back in (the choke is near the drivers left knee, or at least thats in a right hand drive)
3) Sometimes it revs up when not in gear & the power steering is turned, but just drive it as normal, assuming it is a manual
Hope I could help
Having problems with 1985 Mazda 626, won't idle down after it warms up. Have a Haynes manual for that model year, but can't find anything on what to do for this problem. Help.