PO171 check engine light

What is your question?

I had the PO171 code which my friend cleared after I replaced the air filter and connected the tube that goes to the filter (it was not connected when cel came on). I drove the car for 3 days until the check engine light appeared again. The mechanic recommended replacing the maf sensor or cleaning it. I noticed that the 2 screws on the electrical connector needed some special tool. Please help me on how to remove the screws (what tool/s needed) and how to replace the maf sensor and how to properly clean it (what solution shall I use for cleaning). Thanks in advance. Happy holidays!