1986 evinrude 150 engine woes,got some questions

[mushman]

I never checked,I just replaced it, then it fell over in the cooler I had put it in.Should I remove the new filter and see whats doing in there?.
I have the engine manual on the boat, and I will go down there in the am, after draining what should I do?should I try running it, should I drain some or all gas from tank?.I read adding seafoam to gas might help remove gunk is that a good idea?.

Forgot to add, when she starts up it runs 300-400 rpm lower at idle,it does start up right away though.