1998 Altima Mechanic can't figure it out
 

I have taken my car to my mechanic and they can't figure this out.

When I try to accelerate my altima, even when I floor it, the car will not go forward. It will sputter but it will not complete the acceleration. There is smoke that will come out as well. I have changed the fuel filter and fuel injector a couple of times. This becomes a temporary fix, but two weeks later it breaks again.

The mechanic has basically given up.

Help

Mark