We met in your office last week and yesterday I received a letter saying that you have a great position for me.
you don't need this sentence.
Fistof all, the main reason is thatI have been working on a project for many years in a company and I fear that I cannot give that up.
I am working on a project for many years in company, and I'm afraid I cannot...
Moreover, In addition, I would like to recommend another expert to you,
moreover/in addition , just use one of them, it will be OK.
, who is rather professional in carrying out new IT project.
this sentence is not make sense.
if you call me to inquire anything about this person.
here ask will be better,
if you want to know the details about this person, plz feel free to call me
I think you can write down the letter in your own language and then translate to English, it is more easier to understand what you want to say