95 olds 88 code help

[fair67]

Hello
I got a 95 olds 88 royale 3800 engine. It surges upon acceleration from a stop it is a hard surge like when you toe tap the gas.( goes stalls goes stalls and then as you speed up it smoothes out.. hope you understand what I mean) . I believe this car has the ob1 computer and I managed to read the codes with a buddies scanner and 3 came up but I do not know what to do about it.. Here they are.
1) P1257 - Boost control fault system overboost.
2) P0705 - Transmission range sensor circuit malfunction
3) P0171 - Bank 1 system too lean

Any and all help appreciated..