i have an 89 mazda 626 mx its stalling and bucking what can cause this

Hi mc320! This sound very much like fuel filter to me (especially if you like to run your tank low). That's where I would look first! Good luck!

also you might try the ignition control chip located inside the distributor they eventually start losing signal to ground (shorting out) intermittently and will cause stall outs. My old '85 626 did that especially when I would brake (extra power drain) You can try removing it, coating with di - electric grease and re installing or tapping (gently) with a hammer whilst starting it or just replacing it(recommended) Also wait until dark out or go to a very dark area open the hood and start car or attempt starting whilst spraying plain water (use old windex container etc) in and around the ignition components ie coil, spark wires, distributor, etc to see if there are any sparks or plasma streams visible. if you see any then you have likely found your culprit. Replace as required.people always look to the fuel filter but forget about the firing components. Good luck!!!