sounds like blinkers on when its not, gas gauge says i'm out of gas when I'm not

What is your question?

dashboard lights go crazy once in awhile, change oil, ABS, gas and it seems like this all started the same time my AC quit working this hasn't affected the trucks performance

What makes this problem better or worse?

IDK but gas gauge works sometimes after I restart the engine

How long has your 1999 GMC Sierra 1500 had this problem?

3 or 4 years ago but I only drive it maybe once a month