My 99 GT has a mind of its own lately. The problem begins when i come to a stop. The car suddenly decides to rev up and lunge forward. I have to put the car into neutral especially when there are crosswalks and people walking in front of me. My mechanic has tried a couple things but to no avial. I've noticed that the problem gets worse when the car gets hot. I can be at a stop light and it will rev up as high as 1000 rpms and down. The only way I get it to stop is by placing the car in neutral.

 

Run some seafoam through your car! Should take care of your problems! Have you checked your pvc valve, cleaned out your iac, check your airfilter to make sure it's still good and finally if that's doesn't take care of your problems check your plugs...always check for the little stuff first and work your way up.

 

also possible sticky IAC or a vacuum leak.