new idea....
use this to create a new 8v source for the LM.
https://www.amazon.com/DZS-Elec-Conv...dp/B071CWMRYD/
run a 12v jumper straight from the battery into the car.
Run a ground straight from the battery to the fuel rail bolt (just in case) and an additional one straight into the car.
http://minimopar.net/ecu/lm-1987-t2.html
hook the constant 12v to the amazon regulator and set the voltage output to 8v.
wire the new 8v power source to Red LM connector pin 23 circuit N6 18 OR 8V power supply from power module and disconnect the original. (use a radio harness pin so you dont have to butcher the harness)
wire the dedicated ground to Blue LM connector Pin 7 and 8 circuit K9 18 LB/RD* Power ground source from fuel rail bolt
go for drive.
Brian
PS. the next step will be to jumper 12v straight to the LM as well (do it all one at a time) to see if 12v is dropping out.