what troubleshooting or diagnosis have you done. As indicated above, you will have to look to find the problem. could be bad wiring under the cowl, could be bad wiring in the boat, could be a bad enrichment solenoid, could be a bad switch.
dont look to facetube. most of the info is wrong. look in the stickies on this forum. however a failing lower shift cable will delay its action often causing stumbling and in some cases killing the motor while shifting (use google to search for the string "lower shift cable iboats.com" and...
Start googling Mercruiser 470 issues.
If your original voltage regulator still works, no need to change to an alternator.
However if the motor overheats as much as 10 degrees, that motor will eat the voltage regulator and spit the head gasket
Just throwing parts at it and not trouble shooting is taking $100 bills and setting them on fire.
Start with the basics.
Compression numbers, fuel pressure, timing
Drain the block
Take the hose from the transom shield and tee it off with the 2 hoses going to the manifolds. Pressure the block and heads to 15 psi of air. It should hold forever.
If it doesn't hold pressure, listen for the hissing
