92 Eldorado - tachometer flutters
 

I have a 1992 Cadillac Eldorado Touring Coupe that the analog tachometer flutters on. By flutter, I mean... when I start the engine, the tach is pegged way past max RPMs even though I am sitting at an idle. The needle bounces all over the place when I drive, but usually remains near pegged out. Is this a cable issue or a bigger problem?