Outboard at the shop being worked on. Mechanic states that carbs have been cleaned twice. Ran great for thirty minutes on hose. River tested for thirty minutes then turned off motor at dock and then attempted to restart then motor gave problems. Doesn't seem to want to stay running. When placing a load on the motor, motor cuts out. According to the mechanic, motor has good spark and compression, but still has problem. He also swears that he cleaned carbs one more time to make sure carbs are debris free. Motor is being ran on spare tank at this time to rule out bad gas. Any suggestions as to the problem.