I have a 97 GCL 5.2 and when I am sitting at a stop light the motor wants to surge. For example it will idle down to about 500 rpms and then go up to say 1000 back and forth like it wants to die. If I put the trans into neutral it will stop doing this. What should I look for or check.
Thanks for any input.

 

With a scan tool you can find out if the Distributor is in sync. If you have acess to one, or take it to your local garage.....Should be "0" with key on engine off.