ok i have an 01 ss that has been a great car. it has 167000 miles and still runs great. my problem is when its warm inside the car, sits in the sun with windows up or its really hot outside. it does nt act up during the winter. this is what all it does

service engine soon light
battery light lights up
voltmeter does not work
sometimes the radio says locked
sometimes the speedo and tack does not work
sometimes the temp guage doesnt work
sometimes the windows dont go down
sometimes the radio will stay on after car is shut off and door is opened.

anyone have any ideas on this.