I have been reading this thread for a while now and based on a comment about the turn signals, check to make sure the front and rear turn signal bulbs are seated properly. I know the ones up front can be a pain. Check the rears first and if necessary, remove under body panels in front to gain easier access to turn signals.
Also verify that they are the right bulbs. I had installed bulbs that I thought were correct only to have them flash faster than the originals I pulled out.
It might even be easier to remove the fuses for different functions one at a time to see if you can narrow it down that way.
Any aftermarket items like radio, a steering wheel lock bypass unit, or possibly a disconnected plug to disable 1-4 shifts are other things to consider.
I know how electrical issues on a car can be frustrating and difficult to diagnose.