i do not know what motor you have but sounds like the crank sensor and/or the ignition module. On the 4 cyl they are actually together and separate on 6 cyl. Either one can cause this and neither will set a code of any kind. My dad's 89 had the module fail and the crank sensor was in bad shape as well as his (2.5 4 cyl) crank sensor is inside the motor a good ways and had cracks. The module was tested and was bad. if it is getting fuel, I would think it has to be one of these two or even both. the crank sensor controls when it fires and the module gives it the power to spark. have them remove and test. If they can't they can take the module to any good parts store and have tested... It might be firing but weak,or maybe firing at wrong time. Just a thought. Of course Maxwedge might be right, just have to rule these things out.