Hi,

I have problem with my GMC jimmy ''00'' the car accelerate by it self with out push the pedal and sometime it accelerate while I use brake to stop it.Also, when I shift from D to to N the rpm increese then after few seconds the rpm return to the normal idle rpm.

 

Any check engine lights? A bad tps can make the idle too high. Also, I've had cars where the throttle cable would get stuck, and hold the throttle open slightly, creating the se symptoms you have

 

No engine light , I will check the cable and I will test the tps

 

On my old 92 Blazer, I had to disconnect the cruise control because it would not disengage. I was on a local highway and it would not disengage either by pressing the brakes or from the control switch. I had to put it into neutral and pull to the shoulder where I was able to turn it off. I then disconnected the cable from the throttle. You might check yours.

 

Good point about the cruise control. I didn't think about that. Very likely

 

yesterday I replaced the tps and still have the same problem. Also , before this I loose the cruise control cable and nothing change.

 

That is somewhat strange You don't get engine check light on. From what You've wrote:
for me it looks like Your fuel trim system gets over regulated and compensates. Did You check the fuel trims when the above happens?

 

Today after I drive my car to university this problem completely gone and the car run much smother then before after I replace it and no vibration when I push gas paddle like before.

It can be my car need to drive more miles to work better ?

 

Only if You sacrifice a black hen at the full moon each month. I'd rather rely in science here and check ST/FT trims.

 

How I check the check ST/FT trims?