I've seen shreds of Teflon tape get into needle valves and jets, even internal passages in the carb at times, and cause all sorts of oddball mixture problems. I like to the "PTFE" (teflon) brush-on paste sparingly on pipe-thread fittings ONLY, and it's a good idea to leave the first couple of threads on the male fitting uncoated to be sure none of it gets into the fuel stream.
Jerry