one day i was driving my car and i was at 4k then i felt that it not goin faster its just stop and started to drop then when it got to 3k it stared goin fast up to 4k and the same thing happen i gave it more gas this time and nothing it just drop to 3 and did the same thing goin home does any one kno wat it is?

 

Do you still have cats on the car? If big chunks of metal honeycomb break apart inside one, they will cause all sorts of weird power loss at varying RPMs depending on how blocked the exhaust is.

 

Check your fuel delivery system.

 

you dont think it will the fuel pump goin bad because now when i start it it go off and it has gas

 

OK, don't.

 

Umm. I would check the secondary injectors. If those don't work, then I might look into (if you have an S5) the OMP. If thats bad, its going to put your car into "limp" mode. Maybe the exhaust theory has some merit, that I am not sure of.