While we're waiting for Icemanjoker, I also took a quick look at this. I'm by no means a top player, but I think I can offer you some advice.
There are lots of little things I would have done differently, but overall you made three main mistakes:
1) You never dealt with his sniper. Your first engagement with the Stuart should have prioritised the sniper.
2) You never equipped your Riflemen with BARs or Bazookas, yet had all those hundreds of munis.
3) You repeatedly tried to assault entrenched positions. You lost a lot of MP getting your cut-off to the left side/top, but then lost even more assaulting his cut-off to the mid/bottom/right. Why? You had all three VPs, the ability to throttle his fuel, but instead you suicided into the building on his side of the map.
All of this meant that you didn't have adequate support for your Pershing. You over-extended the first Pershing, so your AT couldn't help v the Panther. The fight was really over then. You needed Jacksons to support it, particularly with a Tiger Ace on the field, and the second Pershing never stood a chance 1v2.
At those points where you felt you were doing well, forcing him off territory, you kinda were...BUT you were losing MP and whole squads, and your opponent wasn't.
EDIT - Also, Semosky is the WORST map for USF - veto it.
Final EDIT - Also, if you had teched to Major, you could have had a retreat point on the middle, rather than back in your base.
Thank you very much for the response.
I was just wondering why Semosky the worst USF map?