The Nissan Path

i have Nissan Pathfinder 2006 SE . and i am facing one big issue that is after running my car few kilometers the gear shifting sign on my car dashboard is disappear and when u stop at the gas station and i press the full accelerator but the car is not picking up speed and when you turn off my car and then i want to start my car againe at the same time it wont start and i have to wait half an hour then the car will start .. i don't know whats this issue and i went to 4-5 car mechanic one of them took 135 USD but the car is still the same . please help me regarding this issue