Cat 6nz Engine Flutter Electrical issues

Hey everyone I’m hoping to get some help on here. I have a 2006 T800 with a Cat c15 converted to a 6nz 800 marine came and 8501 injectors and a 550 cat tune with a 70 pin ECM. Truck ran great after overhauling it little over a year ago. Then one hot day in South Carolina stopping for fuel I noticed it ran rough. Kinda came and went but started getting worse. I was told a bad injector so changed it out then another and another till I got all 6 replaced. Then suspected combustion gas past the rings so pulled them all back out and reamed out the seats in the head and new injector rings still there. Then suspected air in fuel so replaced all fuel hoses and lift tubes and valves. New check valves pressure regulator both filter housings hand primer fuel transfer pump even new fuel tanks as one was leaking a little. Same problem then installed a fass system and starting the truck I knew my problem was solved. Lasted a little over a day then back to the problem. Then went to wiring and put all new battery’s all ground and hot wires from battery’s to engine and altenator and fixed a few connections that looked green and a new 4 post solinoide in battery box that looked rusted and put electrical grease on any connection I could find. Swapped out ecm tried different tunes problem still there. Ran many overheads and checked back Lash and timing. Then got rid of the 800 cam and went to a normal 6nz and all new 8501 injectors again including both engine wire harnesses on engine and it runs a lot better but it gets moody here and there and idle is good at 600 but Reving it up to 1000 it’s rough. I’ve done all timing sensors MAP sensor fuel temp sensor has a new turbo since the other one started pushing oil. Checked for air leaks on the boost side. Engine pulls great but it feels like I’m about do drop a driveline out of it when it’s acting up. it has a little blowby but good burns no oil or coolant. never overheats and all fluids look like they should and no engine codes. It is straight piped and no blockage on exhaust side. I’m leaning electrical now. I feel like I smell rotten eggs but battery’s test good and they are almost new. Tried touching them after running all day and also wires nothing feels hot. My Jake brakes seem to weaken up here and there then go back to normal but all 3stages work and already put in a new switch and also ran engine with the solenoids disconnected same thing. Also my ABS light comes on when the trailer is hooked up but only with lights on. Then pushing on the brakes the rear clearance lights want to light up as well. Also my dash lights flicker a little but go back to normal if I mess with the dimmer dial. Speedometer and tack work but odometor quits reading here and there sometimes for a whole day then works again for 2 days. Also fan indicator light wont work all the time but when it does it’s backwards it lights up when the fan is off. Anybody got some advice on bypassing some grounds or wires that could diagnose instead of throwing more money into this thing? This problem is intermittent but more bad days then good. Anyadvice is appreciated