1997 Mazda MX5 Engine missing

Miata starts fine, idles fine and runs fine, except when given gas to excellerate, it skips or misses badly like it is runing on 3 cyclinders. What could case this. It happened a year or so ago and it was the mas air flow sensor. I cleaned the sensor with electronic clearer spray. But no difference. New plugs about 10,000 miles ago.