What year is it (this helps to identify what features might be on your motor), how long has this problem been going on, did it run well in spring when carbs were cleaned? Have you purchased fuel from different station(s) than you normally use?
Does motor run smoothly at idle, do you have tach, to tell what RPMs motor bogs at, our have you checked any filters to see if trash is in fuel?

Post back. A little more info could help you find your problem?

135 Johnson

The motor is a 1974 model I am pretty sure. But I started having the problem last fall and this spring before we took it out I took it to a boat shop and had it repaired they went through the carbs and tuned it up and installed the fuel pump thinking that was the problem. It ran good the first time we had it out but the second time it started doing it again. I took it back to them and they installed 4 new plugs thinking that the old ones were fouled it ran fine for about an hour on the water I changed the plugs again on the water and it did not fix the problem. I am pretty sure that it is not getting enough fuel all the fuel lines to and from the motor are new. I use the same gas and I don't have a tach on it seams to run as smooth as it ever has at an idle when you get it first started and after it gets warmed up it really don't want to stay running very long it starts and dies. The filters are clear don't see any trash in them.
Thanks for your time to help me!