Recently I have been trying to only use a coffee distributor while brewing my espresso. I find that with the coffee I use, the distributor gives it a rounder and floral flavor than if I use a standard tamper. I usually weigh 16g and target an output of 32g in 25-30 secs from the time I hit the pump.

Usually the shots are fine, but there are often times where one shot in between shots will go wildly off time (keeping everything the same). It can be as short as 18 seconds for 32g of output. And If i dump that out and re-dose and pull, chances are, the next shot would be as expected.

Not sure if its my gear, the coffee, humidity, or just a combination of all. Anyone has faced any problems like that?

I use a distribution tool, and I have seen similar behavior. Once every 30+ shots, I'll get a gusher...where the shot runs very quickly and the coffee comes out under-extracted (I assume; they are sink shots that I don't bother tasting anymore). Just as you say, it's a one-time thing and the next shot is back to normal.

I've always assumed that maybe I'm making some unintentional change to my workflow. Maybe my distribution technique was a little off for that shot, or maybe I was a little too rough putting the portafilter back on the machine, causing a 'rupture' in the puck. Since it's always been a one-off occurrence, I just dump that shot and start again, and I live with it. After all, my success rate with the distribution tool is still higher than it was with a tamper (probably because I never developed a great, consistent tamp).

One thing worth noting is I don't "tamp" with the distributor. I have it set so that the tool does very light compression of the grounds, but produces a smooth and (hopefully) evenly distributed puck. But it's still a very "soft" puck, not tamped anywhere near the traditional 30lbs or pressure. What's interesting is that the spent puck holds together pretty well, and often slides out of the portafilter in one clean piece.

Great to know i'm not alone. It really puzzles me as to why it happens. I was attributing it to my coffee as it is quite a finicky coffee to extract with. Even with the good ol tamping, sometimes it would gush, sometimes it would be slow, and sometimes it would be just nice.

My experience with distributors to flatten or "groom" the top before tamping has always been a net negative. I've stopped using them. A quick stir, tap to flatten, and tamp gives me consistent results. I haven't seen a gusher or spurter in a long long time.

YMMV, there is a good chance I was just doing it wrong. But I'm not going to fix anything that's not broke.