2002 Sunfire Gauges going crazy

My Daughter's 2002 Sunfire has a problem with the Gauges and electricial system. I have read the posts here but we are not yet able to fix the problem. So far the Battery, Altenator, & Instrument Cluster has been replaced.
When you hit the brakes to put it in Drive, the blinker lights on the dash slightly flash, but not at ful intensity. Then the gauges go crazy. Fuel from full to empty. Tach & Speedo up and down. RAdio turns off and on when turned on, and interior dome light goes on and off. The key and seatbelt alarms go on & off too. The car does not stall or turn off. She wont drive it.
LAst suggestion was to replace the ignition switch. Dealer wants $75/hr to trouble shoot it looking for a short. They said it could take hours or weeks.
Any input would be appreciated. 33K on the vehicle.

Today problem diagnosed as the Computer. I will let you know how this turns out.

Turned out to be the Computer. Used one $125 plus $50 to install. All seems to be working OK Now.

eather a short or a faulty wirering. i think it would be faulty wirering

I had somewhat similar issues with a fault in the ClassII data bus on a 2000 Sunfire GT. Guages and radio were dead, all warning lights would come on, car would start and drive normally but no instrumantation. Turned out to be a fault in the EBCM (electronic brake control module?) and needed to be replaced.