I had a similar problem with my Mazda pickup, only when I would use my turn signal most the lights in my dash would blink. I thought it was the multi-switch so I bought a new one only to find it didn’t fix the problem. At this point I started studying the wiring diagrams looking for something common to all the lights that would blink and the turn signal. After checking many components I ended up back by the brake lights and it turned out to be a wet corroded trailer light hookup. When I unhooked it everything worked great. So to make a long story longer get out the schematics and start looking for and checking points that are common to all the lights that are coming on.
Front: Dana 30 4.10: Yukon Chrome-molly axles / Super Joints & Lock-Rite locker
Rear: Dana 35 4.10: Yukon Chrome-molly axles & Lock-Rite locker
C & C Fab Tube Fenders (giving these guys a plug because they treated me so well)
Home brew oil-pan/bell housing skid plate and gas tank skid plate.