It could due to a few problems..
1 Gear box - wow - money a lot - replacement SGD10K-12K, Overhaul SGD8K, Recon replacement SGD3.5K to SGD4K
2 Ignition coil problem - Nissan parts original SGD85 per pc from stockist need 4 pc - replacement by workshop sgd65-100
suggest you go to a reputable workshop to check - like Delgro carcare - then buy from stockist, and go to your own workshop to get it done