Pull the carb, tear it down, clean everything, use high pressure air from one of the canned compressed air thingies used for sewing and computers. Use the tiny red directing tube to get onto all the passages.

Depending on the age of the carb, DLE used a sealant around the welch plug that degraded ofver time and flaked away. The flakes, when small enough, would block the high speed passages in the carb, limiting engine operation to half throttle or less.

While you're inside the carb, scrape away any remaining sealant that's found around the edge of the welch plug. Use a toothbrush afterwards to assure that small particulates are clear.