2007 mercury 50hp oil injected carb engine quits while above 1/2 throttle after a few seconds hear rattling noise from engine and motor will not turn over for about 10 seconds but will recrank after that and do same thing.does not appear to be running hot. changed spark plugs and added sea foam to gas tank.any suggestions

Put 50:1 in a small tank of gas and try it, if it runs OK then start checking out your oil injection. there is a check valve in the oil line that can fail and push fuel into the oil. It is a good idea to change it during annual maintenance it is only 20-30 bucks.
If it still happens after adding oil to the then you need to look at your carbs.
Whatever it is you have to find it ASAP, it is doing damage every time it seizes up.
You only get a few times and it will be junk.