Upon reaching operating temp, the engine begins to buck and stall. Ideas?

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Upon reaching operating temp, the engine begins to buck and stall whaen coming to a stop. Got a crank position code so I changed the sensor. Seemed to works at first but now the behavior is back just as bad as before. Grizzled Nissan mechanic at the dealer is betting dimes to dollars it's the distributor not the sensor. A reman distributor and rotor is $260 at Pep Boys with core, $380 with core at Nissan. Thoughts? BTW, no distributor codes but I'm getting an EVAP code also. Thoughts?