Need some advise

[SRYE]

I have a 2005 205 Pro with 225 Opti. I sued to able to turn the 25p Tempest Plus at around 5700 RPMS and get around 68 on the GPS. I don't typically run the boat hard so I am not sure how long it has been since I started having the issues. But, I recently noticed that I was only able to get around 50 mph and only 5k rpms. I did have the spark plugs changed and I had the prop reworked. Yesterday I has able to see a little improvement, such as, I was able to get around 57mph and 5300 rpms. The PTP was at about 4" below pad so I went up to about 3.5" and lost 100rpms and about 2mph. I am going to put the jackplate (manual 10") back to 4" below.
So the question is should I go even lower? I just don't think I am getting the bow lift that I need. I am guessing that 12 years of tackle accumulation is part of my problem. Any other ideas would be greatly appreciated.

ps: The only other thing that I have one is add a large transducer for the Lowrance TI.

Thanks
Steve

[gaboy]

check for clogged injectors also check tuner.

[OldTimer57]

Lots of things sound wrong. Up on plate and down on RPM? That immediately suggests your tach is not working correctly. Also, WHERE did you mount the transducer. Any chance it is reasonably close to being in front of the lower unit when running? Definite no-no if so, as you don't want to disrupt water over the L/U and going into the prop disc.

If it were me, I'd take it to a mechanic and have him check it over. Any of a number of things could cause your problem. Bad coil. Fuel issue. Anywhere in between.

[SRYE]

Yea, I am starting to believe that this is more than a setup or weight problem.