1985 Evinrude carb issues?

I have a 1985 Evinrude 70 hp. It sat for a year but I put in stabill in the cyclinders and ran some through the fuel lines. Took it to the lake and it started fine. Stalled as soon as I put it in gear. Replaced the fuel line, primer ball, in line filter and connections from tank to motor. Started right up and ran great using on the hose at home. No stalling or hesitation. Got to the lake today and same thing, it started ok but stalled as soon as I put it in gear and now it won't start at all. I have looked at other forums and they are very confusing. Is it a carb problem? Since I have a very limited budget is this something I can fix myself using a manual? Thanks for any help.

Do a compression test first.------Then make sure you have spark on all three that will jump a gap of 7/16" with a snap you can hear.----------------No money spent on these tests so far.-----------If results are good then look at cleaning the carburetors , usually no money involved there either.

Thanks for the reply. Will do as you suggest. I just purchased a repair manual for it, hope that helps as well. I am guessing that a compression tester from any auto parts store will work?