1988 25hp johnson problems when tilted

I bought an older duck boat this year. Its a '88 polar craft w/25hp Johnson motor w electric start. The motor runs fine when its all the way down. When I set the tilt to prop the motor up slighty the motor starts to run funny. Starts to cut out almost like it's not getting fuel for a second. Runs fine then bogs for a second then runs then bogs. Kind of a jerking motion to it. Only does this when it's tilted up slightly. Fuel line doesn't seem to be getting kinked. Any ideas. This boat is all new to me.

May want to do the carb on it and be sure to check the float level on it closely.

Hi, I just bought a used fisher marine with the same motor. It does the same thing. Cranks and idles perfect. Runs wide open perfect usually. Once in a while it just starts cutting out for no reason. Let it idle for a minute and it usually clears up. Now it seems to be getting worse. It is pegged on the mount to just before last hole in trim bracket. I'm going fishing today and going to try tilting it down a few holes and see if it helps. Can't afford to pay boat mechanics around here, they make the same as my last divorce attorney. Let you know if this helps, I really an to get it figured out myself.