791 on 92 seviile

need help i recently installed a viper 791 on a 92 seville and the now jumps sporatically all over the place during acceleration and decelaration. any help on this would be of great help

sorry i didn't be more specific earlier the tach is what is jumping everywhere during acceleration and deceleration any help would be great thanks

check the tach wire? I saw something like that happen before on a car when the tach wire accidently touched a part of the engine and shorted out.

Engine is now checking voltage instead of tach. Mechanic said that the tach wire was causing the issue so i disonnected it. Although the problem still occurs even with out the alarm installed. Is something i could of done to cause this problem? The car was working fine for about a week or two before the customer came back about the issue.... Thanks