Back blinkers work very rapidly like front blinkers are burned out. Hazards and running lights work, connections to ground is good, bulbs are good. Any help would be greatly appreciated!

 

Add some blinker fluid
seriously though, are you saying the front blinkers work properly but the rears flash rapidly?

 

Back blinkers work very rapidly and nothing up front. Running lights work (same bulb, different source). Hazards work in the back but not the front also. Good continuity on earth ground.

 

So, if your front blinker don't work...
that is why the rear ones "work very rapidly like front blinkers are burned out".
fix your front blinkers.
start with bulbs, keep it simple. make sure they are good
then check for ground
then find out why you don't have power, (insert wiring diagram here). 99 taco has different wiring than my 95 4runner, so I don't have a diagram.

 

In my post I said bulbs are good and ground is good. Hoping someone has had the same problem and could lead me in the right direction. There's a "J3" connector that has about 15 green/red wires attached and I'm afraid that's where my problem lies.