Guages r messed! HELP

K. i own a 1991 mx6. My whole dash is crazy! its fine while im driving, but as soon as i turn on the indicator, everything goes haywire! my tacc jumps up n down, both signals go on and off and the cruise control light flashes. also when u turn the cruise control light off it turns on by itself shortly. i hope someone can help. alsom my gas gauge is off. its only accurate when my car is idling. as soon as i start driving it drops, then comes up again.
:(

Also. on the brighter side of things. anyone have any clu how to add a few cheap horses? kn filters, muffler etc. any other ideas? and where would i get a cold air intake from?

Thanx