I posted here since Sentra and Sylphy share similar mechanics. My 2006 sylphy lacks power when trying to move from a halt position especially in places that require significant amount of power to move. For instance, reversing uphill from a halt position, i would have to step on the gas (full throttle) for 10 to 20 seconds to atleast expect a response (reverse movement). If it does, normally the movement is too slow. However when there is some momentum, then it resoponds well all the time both on reverse and the drive. Once it has some momentum, its a king on the road as its speed can sky rocket. If i have to go over a bump, i would have to ensure that there is some momentum, without which it may take alot of time before it goes over it. The same thing would happen if i would try to go over a small piece of stone, in other words, no form of resistance is welcome. On a flat surface it responds a little bit faster and more predictable. When all this happens, the rev counter stays still however much i may step on the gas, but only change its position simultaneously with some movement. My mechanic suggested a change of gearbox, then throttle sensor, ECU...all of which did not cure the problem. A friend also suggested the exhaust system which was all checked and leakages sealed to that effect. I cant rely on the vehicle now, especially that my terrain is not that smooth type. I am in Africa, Kenya and the roads can get bumpy. Any suggestions will be highly appreciated. Thanks