Grand vitara loses power while driving slow 2 a

Correct. When you turn off the engine you lose the engine vacuum to the brake boost assist. No brakes. Can't accelerate with engine off.

try hold up the key while starting, shot in the dark. if it startes remove extra items off key ring

weak battery , slow turns.
bad glow plugs.(or controls to them)
bad fuel or water in fuel. (or controls to them)
low compression

replace egr valv and reset computer

i had the exact same thing happen to me with my first car, a 1966 mercury comet.

i replaced the fuel pump, rebuilt the carburetor (twice), and finally rebuilt the entire engine! still, every time afterwards, the car ran ok, then would cut off again!

it turned to be just a $2 clogged fuel filter. i' suspect the same with your vehicle. after removing the filter, simply blow through it. any resistance, means it needs replacing.

I have the same problem but when my esp light is on it causes my engine to rev up when it's in idle and if I put it in gear and try to drive it. It will take off on its own but when I push on the gas it slows it down and if I put it in 1st it'll jerk you back and forth. This has only been happening since the keys for locked in the car and we had to break into it but there is no anti theft light on.

use a scan tool to reset the ECm

check your radiador fluid
your fan also might not be working eficiently
might be good to put some radiador fluid

check front brake rotors sounds like there warped..or it might be in your drive shafts check for looseness

if you don't have a gas cap on the car or if it is on too loosely then that is a possibility. Only other thing I could think of would be water in your fuel. You may try a bottle of "heat" (I think that is how you spell it) at your local auto parts store and chunk it in the gas can. if there were any problems with water that should be the cure.

Michael