Several problems came at same time. Is it my icm or something else?

What is your question?

96 tahoe 5.7l,4l60e trans....my speedo and rpm gauges stopped working. My tranny wont shift unless i shift manually and i cant tell if my o/d is working. My electrical inside and headlights pulse with engine speed. Was leaking trans fluid. Checked it and its fine. Wat could cause it all to happen at the same time?

What makes this problem better or worse?

Worse when at idle. Gets better while driving but voltage meter rises.

How long has your 1996 Chevrolet Tahoe had this problem?

Two weeks