HELP!!!

I think I just got screwed... I purchased a 99 Windstar. When taking over ownership of the van I was told the only thing the van needed was new 02 sensors...
I than got concerned when the engine light came on, the od light came on and some other light (just indicating a light was out).
I than took the van into a dealership and they ran a diagnosis test... Turns out the van came up with a whopping 4 codes P1000, P0741, P0171 and P0301. I was also informed the van had misfires on the #1 & #2 cylinders...
The mechanic said the van will need a new or rebuilt transmission...

Can someone/ANYONE give me any advice... I bought this van bc my cars transmission went and i couldnt afford 2-3 grand to fix that. I am now being told the van needs a tranny too... Im at a complete loss for words and feel like the biggest fool...

Any and all words of advice, wisdom or anything are greatly appreciated!