99 Cavalier- no brake lights, no turn signals

Hello folks, any suggestions would be appreciated.

While driving i recently noticed that when i used the turn signal the blinkers wouldn't work, also, hazards wouldn't work at all. Then shortly after, my wife noticed that the brake lights weren't working... here's some facts..
1) 4-Way running lights still work, front and back
2) Reverse lights still work
3) Replaced all associated fuses (they were tarnished but not burnt out)
4) Replaced all bulbs (10 years old, i figured why not)
5) Replaced blinker/turn signal relay switch (in case it was sticking, no dice)

Since, i've occasionally noted i do have turn signals, but they come and go as they please. It seems possibly like a short or a local ground disruption but that takes alot of digging, any suggestions at all?
Thanks.

see Haynes repair manual pages 12-22 and start testing circiuts...eg.. ground at each light blk wire to body for ground......power supply to flasher , turn/haz. head light switch....... flasherhas own (GRD) and when you activate switch does it run current out switch . ........also recheck fuses for tight fit according to book there are three 3 fuses that lead to lights get book you will need it. also for other stuff you might need to remove to get at switches and light covers checking GRD. you could just pull a part at junk yard.... my suggestion looking at book would be :turn/haz. headlight switch assembly.....let us know how it goes

My hunch is that it is the multi-function switch b/c thats the only thing that the brake lights and the turn signals have in common. but one thing that I've heard is that if the multi-fxn switch goes out than the 3rd brake light will still work. It might be worthwhile to get a switch from a yard and put it in and see if that fixes it.