I have a 1977 70hp Evinrude. All of the carbs have been cleaned new power box/plugs ect. Compression is good in all three cylinders, link and sink has been done. When I put it in gear 50% of the time I can give it full throttle and it takes. The other 50% after putting it in gear and advancing the throttle it will want to stall out untill I "flick" the toggle under the key. (choke?) any sugestions would be great I have been going crazy over this.