Mariner 5.0 questions

[big4uk]

Hi there, i am new to the forum, but firstly great site.

I have recently bought a sailboat and it came complete with a mariner 5.0 outboard.

couple of questions on this -

1) What year is it - the serial number is - 0G847998
2) what is the best fuel mix for this
3) It starts no problem and sits in neutral no problem, however when i move it into forward or revers it stalls the engine. I have pulled and checked the spark plug and all is fine there, so am lost on this one.

Any information would be greatly appreciated.

Thanks
Big4uk