Lumina 3.8L 98 is running worriedly

Hi,

my Girlfriend is for 10 Minutes driving and the 98 V6 3.8L Lumina and then withour warnings, the engine running worriedly.

No Lamps are on, or other things, she drives to park place and want shut off the engine, and press parking pedal and move the transmission to P and the engine gives a little gas by it self, she shut the engine off, and go shopping, so when she comes back and run the engine and drives home all was good.

It was the second time where the car do this, but I cant locate the failure, by the first time I change Oil but this was good.

Last time where did it happened was 1 year again.

It sounds like when she stepped on the brake, her foot might have caught the edge of the accellerator pedal at the same time.

Is it starting and running normally otherwise?

Yes, the engine runs fine now, but I want read trouble codes and bought a device which can VPW Protocol but the device says just no signal from Controller...

What must I do? Start Engine and plug on the device?

The scanner should work with the ignition ON and engine off. Voltage must be present at the DLC. Usually, the power for the DLC is the same as the power for the lighter.

and agoin the faliure....

Can I test the EGR Valve without Scan Tool?