Weird ecu/voltage issues

[Vin_Spin_S14]

Recently picked up a 1993 S14 silvia K and having some voltage issues. I had a Link ecu installed, as well as full bolt-ons and a fuel system, and everything was running fine till I drove it on some very bumpy roads. The car starts and idles perfectly fine. I have a BTI gauge installed and noticed that out of nowhere low voltage at idle and under load, it seems like the ecu is dropping voltage from 10.8v to 6.4v and restarting. If I am parked I can rev it freely with zero issues and if I baby it around my neighborhood I see zero issues. I did some testing with the key on and I have 12.3v at the battery but I'm only seeing 9.35v at the ecu/BTI gauge, and with the car running I have 14.3v at the battery and 10.8v at the ecu/BTI gauge, checking both pins 49/50 and 59/60. I have no voltage on the ground pins. I belive I've located the ecu relay behind the ecu on the passenger side(left kick panel) and seeing the same voltages on the black teaced with white wire that I believe goes to the ECU power pins in the ECU plug. I'm lost and would appreciate any help or guidance. Thank you all very much!!

1st pic is car is idle roughly 750-850rpm, 2nd is voltage measured at battery shortly afterwards. https://uploads.tapatalk-cdn.com/20190615/cde3eed330088d9c2ae3b6292d213649.jpghttps://uploads.tapatalk-cdn.com/20190615/2e0709dfb9e69d11cebed5c80e4e2966.jpg

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[Kingtal0n]

Check all grounds
loose plugs (ecu plug is loose)
all connectors

Also that battery looks way too small

Mainly inspect the computer plugs, and anything that ever been modified. Check for burned cables. Check for loose cables.

[TEN_2nd_BUSTER]

grounds, grounds, grounds, then add more grounds.... get a new battery for sure sized correctly. check engine bay fuse box for corrosion or connection issues as well. basically everything Kingtal0n said..... man i suck