Temp gauge for water is running 160+ or - new impeller and housing good water flow in sea stainer and out exhaust
oil gauge around 240 + or -
oil tank for out drive full
I pulled off each sensor wire no change any Ideas where I should start looking? Engine runs fine a little rough finding Idle it stumbles a bit then finds a happy spot around 800 rpm's
If I need to have the codes checked at a dealer what do I need to ask them to see if they have the proper software for this year?
Thanks in advance for any ideas.

You will need a scanner. I got a Rinda from Teague, it works great and is easy to use.

That is called a Soft alarm on the MEFI-3. Over 3000k rpm it will be solid alarm unless it clears it self

More or less only 3 things set it off on the mefi-3
Oil pressure switch. It is a on/off switch verifying you have oil pressure. Located on the back of the block. You can un-plug it to test. MEFI is looking for it to be a open circuit to ground
Water temperature. Temp sensor that tells the computer how warm or cool the engine is.
Drive lube low. Float switch in the lube tank. You can un-hook it for testing and see it the alarm goes away. Again MEFI is look for it to be a open circuit to ground

For me Merc manual 23 Page 5E-93 and 94

I am going threw the same thing right now. Well sort of. Mine will only happen for about 15 seconds on a cold engine restart.

I think low volts sets it too

That is a solid beep for 5 seconds. But yes low volts also can set it off.