p0rsche23

I just need some help with a couple of these problem codes,lol...

p0113:Intake Air Temperature Circuit High Input(something wrong with IAT sensor obviously...)

p0305:cylinder 5 misfire - fuel injector? dangit

p1151: Lack of ho2s-21 switch-sensor indicates lean(i hope this is just cuzof low fuel pressure)

p0156: o2 sensor circuit malfunction(bank2 sensor2) um i unhooked my exhaust to check the catd and then hooked it back up to the headers and i dont think its tight-exhaust leak

p0171 and p0174 system too lean on bank 1 and 2-im hoping just because of ^^exhaust or maybe fuel pump

the car has way 2 low of fuel pressure or something keeping it from getting to the engine, acceleration is very slow and u cant take off at all-im lucky to get to 65 on highway, and that doesnt last long, usually have to pump the pedal to get it to stay there, umm lets see it idles kinda weird but not bad.....the maf is fine and so should the iat as well but ill go back with my old maf tomorrow and see what happens....fuel filter is fine, cats good, i dont know how to check if its an injector? i checked the sparks and they looked fine...and dangit the fuel pump should be good but it seems as the only thing left to be the problem??
if anyone has any ideas/opinions theyd be appreciated...cant really mod anything if the car doesnt run in the first place lol