mazdafvr
+1y
either your timing jumped (if its backfiring, like BOOM!) lol, it took me a couple of months, my truck had been doing the same, maybe not as bad, but I kept noticing that A. my mixture screws had to be turned In too far for my truck to run right (supposed to be between 1 and 2 turns for weber) and I kept looking, finaly I noticed my brake booster hose was cracked really bad, when I had set the intake aside to do the head and rings, it stretched it. got too much air so I had my screws set to compensate, hints why they weren't where they were supposed to be. id almost guarantee u got a leak somewhere. did u cap the other advance port on your carb after moving it to the intake? does your advance unit leak, try sucking on it and see if it holds suction. when mine runs lean, it does the same thing, rpms drop below idle after rev like its going to die, then picks back up. and I notice a sputter right as im letting off the clutch, sorry for the book.