Greetings, I have a 1987 25hp xd thats running odd! History: It's been sitting for a few years and for the past 2 years ~ it idles fine perhaps,runs good at low speeds, but poorly at higher speeds. Higher speeds (appropriate performance) seems to cut in and out. run at lower speed~ go to full throttle runs fine 15 seconds to a minute or so (it varies). It then starts to die...if you choke it it continues to run. I've changed the gas, replaced the primer bulb, cleaned the tank screen, cleaned the fuel filter. I was leaning toward lacquer in the bowl affecting float movement. I read that it might be a coil issue, however my meter readings didn't give me any indications of an issue.
Lastly I've been unable to identify the model # from my serial # of 0B163264...so tracking down parts is an issue. ** I promise to buy parts from Crowley if any of your readers/staff can help :)** 
Respectfully...Scott