GMC Safari

We have a 2000 GMC Safari (130,000 miles) engine is 4.3 liter. The tail lights and rear break lights continually go out. We have replaced the fuses and then it may work for a couple of days but once again goes back out. We have taken it in twice to an electrical car repair shop to the tune of over $300 but they cannot find the problem and just want us to bring it back for longer (and more expensive) visits. We can use the 4 ways. Any ideas?
Nancy Meier
May 13, 2007.

Its blowing the tail light fuse? Brake light fuse? Do the turn siganls work properly? Need to check all grounds for good contact. Remove th et-light assemblies and visually inspect them for melted connectors/plugs, damaged/pinched wires

May 14, 2007.