72 360 first start question

Hey everybody sorry to leave you hanging with no finale, but unfortunately as I progressed on this build and decided my holley 670 cfm that was originally on the engine wash;t cutting the mustard, I began swapping out my holley 500 cdm off my 340 dart (which is my daily driver) to work on the 360 in the van. Anywho every time i swapped it i had to retune it and eventually the dart had enough and tool a crap on me. I've pent the last week going through all kinds of weird issues with the dart that ran great for the last 5 years. gonna order a new carb for the 360 so I don't have to deal with it anymore. But hears a good question! My Dart always did this sort of thud feeling when braking hard it always seemed to be on the drivers side. After tuning the idle mixture screws almost all the way out it got a lot better but was still there only that caused diesling when I'd go to turn the car off. I've done the put it in neutral and brake test and it's not in the brakes/suspension. Pretty sure it was always in the timing/carb tuning but it was always livable. Now here's the interesting part, as I switched the carb back and forth a dozen times or more and retuned it over an over, suddenly the dart wouldn't start at all and then when i got it running it would cut out like an electrical issue. so i traced everything, remade battery connections at the battery at the starter swapped out the VR and the control module just to be safe and now it runs but i have to advance it quite a bit or give it a lot of throttle. ( which was is the issue with the 360! it's contagious) but the funny thing is the thud knocking sound moved from the driver side to the passenger side and went from only when i was braking hard to once i got up to 25-30 mph and then is pretty constant. I'mnot ruling out rod knock but it doesn't have the metallic tinny sound it's more like a solid thud this thud almost like the granny's hitting the floor but it continues if i put it into neutral. A mophile is defined as someone with 2 or more molars broken down in their driveway. I finally made it. sorry for the novel, been a long strange trip.