how bad will loose spark plugs make it run?

so i have been having an issue with my kz1000m1 with low speed stumbling. it popped up about 2 weeks ago and i found some bad throttle seals. so i ordered and replaced all 8 seals on my bs34ss carbs and finally got them back together and back on(there were some other self-induced issues like mia float needles and buggered pilots :blush: ). so i go for a test ride after getting the carbs back on and the problem is still there, only now it's popping out of the exhaust. initially i found i needed to tighten the boot clamps, even there were no evident leaks, and the boots are brand new last year, no cracks and still nice and soft. so i pull it back into the garage since i can't find any leaks and decide to look into the ignition. i test volts at the coils, good there at 11.8vdc, battery showing 12.2 vdc. next i go to pull the plugs and see how the spark is, and found all 4 loose to the point i could have used the socket with extention with no ratchet to take them all out, and the plugs haven't been out since last year. the spark is nice and fat purple/blue, so i'm good there. but could i have found my culprit with the loose plugs?

That'll do it. Hope the treads are OK.
Steve

threads are good and tightened back down just fine, but unfortuneatly not the problem. moving this to carbs

If popping through the exhaust on deceleration, could try slightly enriching the pilot circuit in each carb (say 1/4 turn), and test ride.

Good Fortune!