I have been very satisfied with my 87 Outboard Force Motor. Recently, when I tried to start the motor I was not able to keep the motor running unless I removed the motor cover. Once removed the motor ran fine. After I throttled up the motor I put the cover back on and the motor runs fine as long as I am running the motor faster than an idle. As soon as I throttle down the motor I must remove the cover or the motor shuts down. Is this a carb. problem and the motor can breathe?