i have only had this problem with my old Honda the timing belt was off a few teeth.. i would check your timing in general, maybe you have one of the plug wires in the wrong place and then go a head and check your timing belt itself for wear and signs of stretching

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1998 Mazda B2500se 150,750
Just changed the battery for the first time!
timing belt and water pump at 136,000
Brakes and Tires and that's about it.
and every 2 years a DPFE sensor

7" Jensen flip out (VM9213)
Two 12.2 sun visor monitors modded to work with OEM brackets
pioneer 6x8 speakers all the way around
single 8" bazooka tube with a 500 Farad capacitor

http://i15.photobucket.com/albums/a3...051909_004.jpg