THE 0S 140 IS A FANTASTIC MOTOR. I OWN 2 OF THEM AND THEIR GREAT. I HAVE HOWEVER, COME ACROSS 2 NEW MOTORS THAT DO EXACTLY THAT. IDLE FANTASTIC YET LOAD UP IN THE MID RANGE TO THE POINT WHERE THEY STOP. I THINK YOU'LL FIND IT IS A FAULTY PUMP THAT SHOULD BE RETURNED TO THE DEALER. EASY FIX.. PULL THE BACKPLATE/PUMP OF ANOTHER 140 AND TRY THAT. THE FAULTY PUMPS WERE ON MOTOR'S PURCHASED WITHIN THE LAST 12 MONTHS.