We have a gremlin living in our 96 Sentra. It reveals itself intermittently. Its characteristics are-rough idle so rough the engine stalls. Sometimes I can feel a hesitation or drag at highway speeds. I have exhausted 3 mechanics with this problem 1 of them a top Nissan wrench in our area. We have replaced the Distributor,idle control motor and several sensors including the crank sensor. I have $800.00 into this problem and still haven't nailed it.. The car runs great when the gremlin is sleeping. HELP!!!