mate in 4

Mate in 4 moves.

This is random and 100% certain that it isn't the right answer, but I am thinking..
Pxf7 PxR=Q
PxR=N+ Kg7 (forced)
Rg5+ KxN
Nf6..
and all they can really do is Qa1+ delaying Rg8#. I know it's wrong but I can't solve Mate in 4's in my head. Even though mine is mate in 5.
Edit: Typically, just after my post I've seen the Queen on c1 has the chance of taking the Rook on g5.

Now trying:
Rf5+ KxR
QxP+ Kg5
Nf3+
That sort of thing.

1 exf7! threatens 2.fxg8N+ and 3.Be5+, or 2.fxg8Q and 3.Qf7/g6#

1...d1=Q 2.fxg8=Q Qxd4+ 3.c4! an important move which pins the Q 3...Qe5 4.Qg6#
1...d1=B 2.fxg8=B! stalemate avoidance 2...Kg7 3.Rf5! preventing ...Kf6 Kxh8 [3...Kh6 4.Bf8#] 4.Be5#
1...d1=N 2.fxg8=N+ must operate w/check now 2...Kg7 3.Be5+ Kf8 [3...Kh7 4.Qxc2#] 4.Rb8#
1...d1=R 2.fxg8=R! stalemate avoidance, again 2...Rxd4+ 3.c4 Ke6 4.Rg6#

This is a Babson task. White answers all promotions on d1 by promoting to a piece of the same type.

Here are the other necessary variations to complete the solution.

1...dxc1=Q 2.fxg8=Q! Black has only one check before succumbing to Qg6/f7#
1...Kg7 2.fxg8=Q+ Kf6 3.Qg6#
1...Rf8 2.Qxc2 Rg8 3.Qg6+! Rxg6 4.f8Q#
1...Rc8 2.Qxc2 Rc4+ 3.Bxc4 Kg7 4.f8=Q#
1...Rxh8 2.Qxc2 Rg8 3.Qg6+! Rxg6 4.f8=Q#
1...dxe1=N 2.fxg8=Q etc.