Loss of power when warmed up

[jonweber124]

I have a 1996 Johnson 70hp outboard. 3 cylinder oil injected. I have had absolutely no problems with it until last year. Towards the end of the year every time I'd take it out after about an hr or so of running it, it would start to choke itself out to the point where it wouldnt start. just crank crank crank. Id wait about 20-40 minutes it would start again. I believe its a electrical issue more so than a fuel issue. Can anybody shine light on this subject for me? I dont really want to pay shop labor rates of 150$/hr to just diagnose it.

PLEASE HELP!!

[boats.net]

Run a compression test. Check for spark on all cylinders when it quits.