looking for the symptons for a bad o2 sensor, map sensor and a vacuum leak.

 

Have you checked for any stored diagnostic engine codes?

You can check the o2 sensor with a multimeter.

The FSM shoes poor accleration and stalling as syptoms of a faling input from an o2 sensor which inturn can clogg up a cat.

Vacuum leak generally manifest themsleves in hunting and/or high idle.

I don't know about the MAP sensor, but when I popped the hose off mine the car would barley run and put out thick and dark plumes of black smoke...unburned fuel.

 

A bad O2 sensor is similar to a fouled plug. It results in poor response, a 'rich' feel on tak off's and some times a little bucking .

I usually change mine every 15k miles, it's only a few bucks, so you might as well make sure it's in good working order because the A/F reading is very important to our cars.

 

what o2 sensor is good? i called mazda and their o2 sensor is 150US man. can i get a aftermarket one instead?

 

Just go to your local parts store, they will pull your car up in their database and they will(should) have a universal Bosch or something along those lines. I can't remember how much...maybe $7-$15, they're cheap.

If you ever want to run race gas, you can get a heated O2 sensor from a Ford($30?), that way the lead won't build up on the sensor.