what to watch for to change map sensor

my truck has been giving me some problems lately, first of all, i jsut had my tranny changed, an now when i start to drive the engine revs until it changes gears from gear 2 an gear 3, once past 60km/hr it stops, also when i try a pass a vehcile, the engine would reve high then would bog out slowly, an other times it sounds like it would back fire at slower speeds, im very new at this, an need some help, i keep hearing different things from whoever i ask, i was told it might be s a map sensor, any suggstions out there?

hook up an OBD II scanner and find out the trouble code

these are the codes:
P0101 Mass intake Flow Circuit
P0141 Heater circuit Bank 1 sensor 2
p0158 02 Circuit high voltage
p0161 02 heatercircuit

are these easy to repair myself or to change the part,

there is a hose hanging from my tranny, its rubber. would this be for teh vacuum modulator. i do ahve problems with my tranny shifting from 3rd to 4th gear, this would be on a regular occurrence, plus the engine would have a higher then normal rpm before shifting, where is this located, an how do i put it back on.

wow this is bad... my brother has the same year avalanche (2WD version) & it needed a transmission already? how many miles on it?

who changed out the transmission? maybe they cut/pinched some wires in the process; i'd try to check those circuits mentioned before changing out parts

transmission is electrically controlled; i'm guessing it's a vent hose but i don't have my brother's truck here to crawl under and check for you

lol, well i never thought it sounded that bad, but yeah, ill have to take in for sure, this is something that needs to be done by a mechanic, it has 190km on it, changed the tranny at 165km or so, not exactly sure on the amount of km it was changed at, an for the hose, thanks, gives me more reassurance that it was a vent hose. the codes that i gave you, are they something that i can do, or do i really need to take it in, i was thinking of taking it mr, transmission,