Does anyone know how to tune a 1.8 DOHC 323f to perfection or does this need to be done by a Mazda Service center ONLY by computer.

The Mazda service center have already tuned the engine twice, but the car seems to have no go like before.

Any advice welcome.

Go to any of the Escort,EscortGT,Tracer OR Mazda Protege web sites-look them up in Google-and you'll find a lot of very helpful info. there.
Just remember that dealers tune the cars to factory specs and this is usually not as thorough as an enthusiast tuning their own car. It would also help to pick up a Chilton manual for any of the models I mentioned earlier; be sure that it's for the 1.8L DOHC engine model year that you've got.