Suzuki DF 20 starts very hard and doesn't idle...

Recently I bought one Suzuki DF 20 carburetor, made 2011 and after some checks on low speed start using the motor normaly ... in the beginning no complains - starts easy, runs very good on high RPM - 4.40 m boat with total weight of 600 kg goes on plane easy and keep speed of 30 km/h, but
After 2-3 days I felt slight cut in power when throttle and in one moment the motor stop when I disengage the clutch - just didn't keep idling After I could restart the motor very dificcult and still no iddle - only high RPM, on low RPM starts 'caugh' and dies. Checked spark plugs - seems it has good spark... just in case I replaced them, but still same. If someone has an idea - please help.... now I'm thinking it can be water in fuel cause it was raining day and the fuel tank was outside, or carburetor jet clogged - the tank is brand new and may had some dust inside

THANK YOU VERY MUCH for your quick and helpful replies my dear coleagues I was waiting, waiting and finally dissassembled the carburetor, cleaned, reassembled and now my outboard is running line new... honeslty - I didn't get any help from this forum... sorry, but this is the ugly truth