Scotty, I have a 2003 GMC Safari that is plaguing me with issues.  I think I have narrowed all my issues, for now, to be electrical. 

1. using a test lamp, unplug the battery neg cable and connect test lamp to lead and put the tip on neg terminal I get light.  I have pulled every fuse and relay 2x and the light stays on.  any frays I have found I have fixed. short is still there.
2. the van will be driving fine, but then hit a bump and it will die.  if I push the accelerator the dash goes crazy.  Brake/Batt/ABS light will flash.  sometimes the voltage will drop on the gauge and then let off the accelerator and it will go back up. in P or N rev the engine no problems.  R or D and push the accelerator, blurp, blink problems in the gauge cluster and sounds like it will die or it will.  
3. The Voltage drop test is, I think letting me know I need a new alternator?  Max Voltage is 13.8 when running. 
4. There was a black with white stripe cable that was connected to the ECM ground cable at the thermostat. I needed to fix the ECM cable due to fact it had a butt splice on it.  I tested the ECM cable back to the fuse box.  I tried to tone the blk/wht cable but it won't hold a tone so I thought it might be shorted.  But testing it back to Battery there is continuity on the negative terminal, so it is a Ground cable correct?  that cable is currently not plugged into anything.  I am thinking I have to manually pull it to figure out where it goes b/c it wont hold a tone.  since pulling that blk/wht cable my misfire codes have gone away.  (I was battling p0302 and P0300 for while - thinking it was mechanical it has passed all tests - Fuel leakdown- new SP and SP wires, new Distributor- compression is all good, cylinder leakdown passed and I couldn't find any vacuum leaks)  like I said since taking that cable out of loop those codes do not exist.  
5. only code now is MAF.  P0102.  If I plug it in, runs rough and starts misfiring, but only P0300 and is pending not stored.  if I unplug MAF it accelerates poorly but the misfire go away.  But electrical issues take over...

Any help would be greatly appreciated.

Thank you,

Jason