Dash Gremlins - Electrical

I need some guidance on trying to fix this pesky issue:

This issue started up this year and I have been trying to figure it out all summer. Everything thing is fine with the electricals when the lights are off, but when they come on things start to go weird. I first noticed this driving in the rain. The head lights were turned on and the dash turn signal indicators started to glow, but the fender mounted ones did not. The temp gauge and the fuel gauge started to move to the right (as if the gauges were being grounded) and the dash lights also dimmed. The ammeter showed a larger than normal state of discharge but would go into the charging side of things when moving. At first I thought this only happened when the car got wet, but everytime I took it out this summer at night and the head lights were on the temp gauge would read like the car is over heating (this car NEVER runs hot), some times the gas gauge would move, sometimes it wouldnt. The dash turn signal indicators would glow on and off without the fender mounted ones following the same pattern. and the dash lights would go dim with the ammeter showing a slight discharge.

One of the frustrating things is I could never replicate this situation when sitting in the driveway... so my time to diagnose this situation has been less than optimal.

This only started happening this year. Last summer I did not have this issue.

The changes to the electrical system I have made since I got the car on the road in 2008 and verified working great last year are as follows:
Electronic Choke
LED tail lights (selected by slantsixdan)
LED compatible flasher (selected by slant six dan)
HELLA H4 conversion front lights (selected by slantsixdan)
headlight relay harness (cracklebacks)
electronic voltage regular from yearone

The things I have done to see if they contributed to this issue:
unplugged the turn signal flasher - no help
disconnected the turn signal switch - no help
removed the fuses from the relay harness, connected the headlights back to the car harness - no help
replaced the headlight switch with one from autozone (slantsixdan said to get an NOS or NOS style one, but I have not been able to find one, so I went to autozone) - no help
inspected the harness under the dash and under the hood - no missing insulation I could see

I talked to slantsixdan and crackleback about this issue. They gave me some ideas that I tried and nothing seemed to help.

One thing I did notice last night (this is with the relay harness disconnected) is that the gauges and dash lights would go through what is described above for the first 5-10 minutes of driving but then everything would settle out and go back to normal. I may try to hook up that harness again to see if the same thing happens. But this almost sounds like something is not right with the system, but once it is heated up things go back to how they should be.

anyone have any ideas on what or how I can check something to try and get this problem resolved?