multimeter goes crazy bad emi?

I have 1991 Camaro and relocated the battery in the back for the motor build. 

Heres my setup:

I have a GND from batt to frame, batt to motor, and motor to frame.

The 1/0 welding cable for my power wire runs to a kill switch from the batt then to a distro block in the engine bay where the same 1/0 cable goes to my starter.

I also have two alternator charging leads going directly from the alt to the starter and directly from the alt to the battery (or kill switch...doesn't matter).  As a bonus I have the alt grounded with a 4 ga.  cable from the alt case to the motor.

Heres my problem:

Whenever I take a multimeter and put in inside the engine bay or in the trunk area it goes crazy!  It jumps constantly to very random numbers.  No one I have spoken too has ever seen this.  I am thinking very bad EMI from somewhere but I have resistor type spark plugs (I'm pretty sure), I have tried several types of spark plug wires, and this has done it on two different distributors!

I just don't understand and am helpless at this point.  Anything anyone can suggest is very appreciated.

Battery is good.  It is on the correct setting and goes crazy while in the air.  I don't physically have to touch anything.

I thought it could be the very low resistance plug wires but a dfferent set of "supressor" wires gave no improvement.  Same with the spark plugs (I am using the resistor type plug).

I was running low volts but (at least for a short time) an extra alternator charging lead directly to my starter solved that.  I have also ran another ground directly from the battery to the motor.

It doesn't seem to affect anything but I also don't have a stereo hooked up at the moment either.  Still clueless.

Touch the two probe tips together and see if things calm down.. I suspect they will. It's not uncommon to induce readings from the test leads in free air.. if the reading settles down when you touch the two tips together, and you don't see any other problems, don't worry about it.

Jim