I've posted about this problem before but it has recently become more of an issue and is a regular problem when I drive my car every day:

As soon as I take the car out of park, the problems begin... gauges dropping and then swing back up (will do this sporadically every 5 seconds or so when driving)... warning lights, such as check gauges, service engine, theft system, ect.. will go on (some will go back off, usually they stay on till I turn the car off though)... stereo only plays at low volume when driving (once I turn it up, it begins to cut off its power ever 2 seconds) at a stand still it can play louder volume.... headlights also seem a little dim and the A/C doesn’t work all that great when driving.

None of these problems affect the driving of the car, but the gauges and the stereo issue is a huge annoyance for myself and other passengers. The car is an 04 cavalier which has had a stereo installed by me, subs and amp installed by best buy, viper alarm installed by best buy, shift plus installed by me, and an intake installed by me. Could any of these things be the cause of my problems?? Like I said, I had this problem before just not as severe, only recently has it become so regular an issue, even though no mods have been done recently.

If anyone could help me out here, I'd be greatly appreciative! Any suggestions or comments, please feel free to post.

Thanks!!

Bad ground off the battery.

it could be a shorted class 2 data wire. The same thing was happening to my car and i tore the whole thing apart(complete dash removal) come to find out the harness going to the pcm where it goes under the radiator support there is a sharp edge of the metal and it wore through the wire loom and right into the purple class 2 data wire. i had to cut this piece of wire out and solder a new piece in. then i hammered the metal flat so it wouldn't happen again. If you need a pic of the location email me at dcstang67@aol.com.