Engine Mechanical problem
1987 Nissan Pathfinder 6 cyl Four Wheel Drive Automatic 100000 miles
I can start the car at any time, runs smooth for five minutes. Then idle starts up and down. Pull in gear smooths up. Be going down the road can fill the car rpms go up and down then it will stop for awhile then start all over again. What causes this and how can I fix it?