Low RPM? On 1991 30hp evenrude

Address transom?

Appears to be flexing too much.----And come to think of it many older boat have foam flotation.----I seen it many times where foam is water logged .--Resulting in poor performance.

It’s a fair comment...Under normal running conditions I'm pretty sure there is very little movement in the transom. However I will address ��

Ok Clever boaters & all who added to by plea
Although I have been unable to test on the water... I’ve managed to do some tests from advise & my own trouble shooting....
Firstly, using my hand held tachometer I established that my gauge (clock on the dash) was more than 500rpm out of sync!
Idle was very high at about 1200rpm!
Did drop test on plug leads....both showing good equal drop....only tested at low rpm with muffs.
pulled plugs & both show equal good signs.
Also...Thank you JR. linkage was pushing against itself, due to setting up at engine & not at remote control.
So add all that up & it amounts to a lot that was wrong. I will cylinder test when I’ve got my dirty clothes on, but I’m pretty sure there good.
Guess I just gotta get on the water again now & test under load
Thank you for any input clever boaters....this forum is a marvel