04 mercruiser 4.3 mpi loosing rpms

[Winder]

I have a 2004 sea ray with a 4.3 mpi, motor runs excellent,no missing or backfiring or popping,but as I try to plain out when I hit about 2600 rpms it won't climb any higher feels as if bogging, if I feather the throttle on an off it will climb on up and plain out, then run OK, but as day goes on each time I plain out it gets more difficult and where earlier in day I could top 4000 rpms it gets less to where I can only get 3500 then 3200 and I can watch it drop rpms with WOT any ideas?

 

[Bt Doctur]

fuel delivery problem or bad dist cap is you use the flat style

 

[Winder]

Yes it is the flat one, I will pick one up and try that thanks