1983 40hp no power

[alrfetting]

My 1983? 40hp Mercury SN# 6279681 has no power beyond half throttle. It starts and idles fine but when I go to get on plane it boggs out at about half throttle. If I back off the throttle it will idle again without killing. If I keep holding it wide open it eventually dies. It runs fine and revs up fine in neutral. Any suggestions as to what the problem is? Has been sitting for a while (4-5 years or more) Wiring looks fine. Just had carbs cleaned, spark plugs replaced and water pump rebuilt. I've only been running it about 2 - 3 weekends since I've put her back in service. It never had great power and I thought it was because it was sitting for so long and would get better on it's own. It seemed to have power more like a 25hp than a 40hp. Now it has power like a 10hp. Compression is 135 and starts on 2nd pull when cold if I don't over choke. 3-4 pulls usually. I've gone on long enough. Thanks for anything.