[nascaracing]

I have a 07 GT500, I purchased it brand new about 8 months ago. After having the car for about 2 months the throttle body went out in it, and had to be replaced by the dealership. Since then the car is acting likes it's missing. If I accelerate it's fine, but at steady speed it's like it chokes for a split second, also if I'm exiting an off ramp and put the car in neutral and let the speed slow down on it's own, the RPM gauge will go from about 1300 to 100, and some times it will just shut off. I have taken the car back to the dealership several times, and they claim they can find nothing wrong with it. Also there are no engine codes being displayed. I also took the car to Pro-Dyno and had them dyno it, along with a SCT calibrator put in, and it seemed fine for about a week, and then it started doing it's same ol thing all over again.

I'm wondering if anyone has come across this similiar problem, and if so what was the fix, if any. I appreciate any and everyones help.

[stlwagon]

Sounds like the throttle position sensor on the throttle body may be defective.

[nascaracing]

But would that not have been found out by the dealership when it went in? As a matter of fact they have had it twice for the same thing, and still couldn't find anything wrong with it.

[Gary Paul]

I was going to jokingly say it sounds like an "operator error" or a defective driver.

But you state that you purchased the brand new '07 GT500 just eight months ago. It had to have been built at least several months (or even more than a year) before that. Now I haven't been driving my '08 GT500 at all since I took delivery over a year ago, but I do have it on a continuous battery charger/conditioner and I start it every couple weeks and run the engine for at least a half hour each time. I wonder if the car just sat at the dealership for all those months or if it received the attention needed to properly maintain it?

[GT500Girl]

That sounds really strange and I've had no problems at all like that with mine. It almost sounds like a fuel problem like a filter or something. You'd think the dealership would of figured out the problem. If it's not throwing a code though...it can be hard to diagnose.

That's a good thought Gary...you should find out how long it was sitting and maybe go from there. Let us know if you get it figured out and what it was.

[travelers]

I would take it back and have the dealer check it. With a different T/B it could be what Stl. said or it maybe a elect. plug thats has some little corrosion from sitting for so long and is causing the problem.

[nascaracing]

It has been back to the dealership twice. And both times they claim to have test driven it, and it doesn't do anything for them. I'm setting up another appointment with them to take the lead tech out myself in the car. Hopefully it will do it when he is with me. Like I stated before it doesn't always miss all the time. I'll keep you people posted if I can get it to do it with the tech with me, and then what they do to correct it.

[GT500Girl]

Try having them flash it back to stock or use your SCT handheld and put it back to stock and see if this helps.