1980 25 HP dies when throttled up in gear

[aronf_53]

I have a 1980 Johnson 25 HP outboard, 25TECSA. It idles fine, and starts fine. When you throttle it up in gear it will gain rpm's for about 5 second then start to die unless I throttle it down. So when your in the water you have a max speed of about 3-5mph. Here is what I've done so far to try and fix it. I have replaced the needle and seat, and float in the carburetor, as well as cleaned it out. I have replaced the fuel pump, fuel lines, fuel tank and gas/oil mixture. I just compression tested it and both cylinders come in at 125. I think it's getting good spark. I pulled each plug wire off separately while it was running, the engine continued to run but not as well. I really don't know where to go from here and would like some help before I throw more money and parts at it. Thank you.