How do I find out what it's flashing at me mean?

What is your question?

The motor is running rough at an idle, but when you put it in gear it starts getting really rough.sluggish on exceleration.the radio and heater controls are working in unison flashing codes at me and the radio won't play.for awhile it would beep the horn as you turned the key just one beep though.it sounds like a sewing machine that is in a bad way

What makes this problem better or worse?

It's worse when it's warm.and sometimes won't start for 15-20min and only after cycling the key a few times

How long has your 1996 Buick Park Avenue had this problem?

A couple months