85 90hp Evinrude V4

[bostonwhaler]

Hey Folks

I have a 85 90hp Evinrude. Its a power house when it runs well. Ocasionally when I run at full out it will give me surges of power. I can not get it to full RPM but then will surge to full WOT RPM for 2-3 seconds and then die back about 1500 RPM, then surge then Die. I have not noticed any pattern as to what would cause it. I have used premium fuel from different gas stations. No Pattern to the result. It does not do this consistenly either. I can run it 5 days and be perfect, then it will do it again. any help would be great

I am assuming its a fuel issue. but not sure what the issue is.
thanks in advance