Timing

I went from a 98 GT to a 94 because I wanted the 5.0. The car seems to be running lean and is getting really bad gas mileage. The plugs are really white looking. I was told to check the timing to make sure it was around 12 degrees. My question is how to check the timing on the 94 5.0. I was told that besides the normal hookup to the timing light which I can do that there was a plug of some type that needed to be diconnected to prevent the computer from trying to adjust it.

Can someone please help.

Thanks.
Jimmy

Thanks for the response. Thats what I needed to know.