2005 25hp Hard to shift into reverse

[Poonpontoon]

Hello, I bought my 2005 mercury engine last july and it had been sitting a while so i put a new impeller on it. It ran fine for a few months and now its has heavy resistance shifting into reverse with the shift lever. Its a side console boat so its got the steering wheel and normal shifting mechanism for those types of boats. Wondering if i need to take it and get it inspected with a marine mechanic or if its something simple like shaft adjustment or cable adjustment.... one other thing if i let it sit for a few weeks then take it out it will sometimes bog at full throttle, wont get on plane but wont cut off. I had resolved it with some fuel cleaner so curious if it was trash or if i should look into rebuilding the carb as its an issue im running into a few times a year. Thank you