My daughters 96 altima had hesitation/misfire issues shortly after we bought the car, just off idle when warmed up it would try to stall. This is common on high mileage altimas due to carbon blocked egr passages. You can check for this by unplugging the egr. If the car runs fine with the egr unplugged then the ports are blocked with carbon. Having a couple blocked ports can cause too much egr flow to one or two cylinders, causing misifres or rough light throttle performance when warmed up. A year later the car developed severe bucking/stalling issues with 253k on it. I am relentless when chasing problems like this. I changed the cap, rotor, plugs, plug wires, swapped out the distributor with a scrapyard one, ran some fuel injector cleaner, tested the fuel injectors, tested the maf sensor, swapped the tps with a scrapyard one, etc. I eventually discovered an occasional double spark going to random cylinders by watching a timing light. Had to be ignition. There was no oil contamination in the distributor, but it turned out there was a film on the optical sensor itself on both of the distriubutors I had. I took a thin narrow piece of carboard (coke fridge pack cardboard) with lens cleaner cloth wrapped around it and carefully ran it through the space between the slotted wheel in the distributor and the sensor itself, thus cleaned the lens and the bucking problem completely disappeared. Problem solved !!!!!