I have a 2005 sanger v230 mercrusier 350 mag. When we reach mid to full throttle it sputters and loses power. Boat will start just fine and idle or go slow and sometimes acts like no problem but then after about a minute or so will start acting up. The gauges are also cutting out when this is happening. We have replaced the fuel filter and the MDC computer for the gauges as well as all of the gas (in case if there was water) any ideas what to check next?