Engine Performance problem
2003 Nissan Sunny 4 cyl Front Wheel Drive Manual 250000 miles
My car Nissan Sunny 2003 is running poor in heigher speed gears (4th and 5th). Very difficultly it achives 120Km/h. The engine RPM are reaching to 3000 prm and no more in heigher speed gears but are reaching to 7000 in nutural and in lower gears. Cleaned fuel injetors, replaced spark plugs and replaced fuel filter also but no luck. Please suggest possible cause and solustion.